The Back-and-Forth Sequence
Matlab (score=230,n=inf)

function w(s,f),b=[];e=0;for i=s:f,a=dec2bin(i);c=find(a=='1');g=numel(a)+1;if numel(c)&gt;=g/2;if mod(g,2)==1,fprintf('%d ',g);else,d=c(g/2);fprintf('%d ',2*d);end,else,fprintf('%d ',g);end,e=e+1;if(e==100),e=0;fprintf('\n');end;end



The function takes s as starting index and f as ending (type inf if you want to keep on to infinite).
The function can go forever without any remarkable time-lag between any two outputs type h=1000000000000000000000000000000000000000000000000000;w(h,h+1) to make sure.
The algorithm follows a mathematical approach that i will explain later, and it does confirm Martin's referenced list, basing on this program:

stored=[2, 3, 3, 4, 6, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 10, 6, 10, 8, 8, 6, 10, 8, 8, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 14, 8, 8, 8, 14, 8, 14, 12, 12, 8, 8, 8, 14, 8, 14, 12, 12, 8, 14, 12, 12, 10, 10, 10, 10, 8, 8, 8, 14, 8, 14, 12, 12, 8, 14, 12, 12, 10, 10, 10, 10, 8, 14, 12, 12, 10, 10, 10, 10, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 18, 10, 10, 10, 10, 10, 10, 10, 18, 10, 10, 10, 18, 10, 18, 16, 16, 10, 10, 10, 10, 10, 10, 10, 18, 10, 10, 10, 18, 10, 18, 16, 16, 10, 10, 10, 18, 10, 18, 16, 16, 10, 18, 16, 16, 14, 14, 14, 14, 10, 10, 10, 10, 10, 10, 10, 18, 10, 10, 10, 18, 10, 18, 16, 16, 10, 10, 10, 18, 10, 18, 16, 16, 10, 18, 16, 16, 14, 14, 14, 14, 10, 10, 10, 18, 10, 18, 16, 16, 10, 18, 16, 16, 14, 14, 14, 14, 10, 18, 16, 16, 14, 14, 14, 14, 12, 12, 12, 12, 12, 12, 12, 12, 10, 10, 10, 10, 10, 10, 10, 18, 10, 10, 10, 18, 10, 18, 16, 16, 10, 10, 10, 18, 10, 18, 16, 16, 10, 18, 16, 16, 14, 14, 14, 14, 10, 10, 10, 18, 10, 18, 16, 16, 10, 18, 16, 16, 14, 14, 14, 14, 10, 18, 16, 16, 14, 14, 14, 14, 12, 12, 12, 12, 12, 12, 12, 12, 10, 10, 10, 18, 10, 18, 16, 16, 10, 18, 16, 16, 14, 14, 14, 14, 10, 18, 16, 16, 14, 14, 14, 14, 12, 12, 12, 12, 12, 12, 12, 12, 10, 18, 16, 16, 14, 14, 14, 14, 12, 12, 12, 12, 12, 12, 12, 12, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 12, 12, 12, 12, 12, 12, 12, 22, 12, 12, 12, 22, 12, 22, 20, 20, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 12, 12, 12, 22, 12, 22, 20, 20, 12, 22, 20, 20, 18, 18, 18, 18, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 12, 22, 20, 20, 18, 18, 18, 18, 16, 16, 16, 16, 16, 16, 16, 16, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 13];
b=[];for i=1:numel(stored)
a=dec2bin(i);
c=find(a=='1');
if numel(c)&gt;=(numel(a)+1)/2
if mod(numel(a)+1,2)==1
b=[b numel(a)+1];
else
d=c((numel(a)+1)/2);
b=[b 2*d];
end
else
b=[b numel(a)+1];
end
end
for i=1:numel(stored)
if (b(i))
if b(i)~=stored(i)
'error',
end
end
end

Since the algorithm verifies 2048 first testcases, I will blindly assume it would for any test case, so my algorithm works regarding few properties i discovered in this process without the pain of shifting and moving pointer:

1- if the twice the number of 1's in binary translation doesnt exceed the length of the sequnce L so the output isL+1 

2- if the sequence length is even and the previous condition isnt set so the output is same L+1

3- otherwise, the output is twice the L/2th index of 1.