Count from 1 to n in Negabinary and Negaquaternary
Julia, 124 81 73 bytes



n-&gt;(a=2863311530;b=3435973836;[base(2,(i+a)$a)*base(4,(i+b)$b)for i=1:n])


This creates an unnamed function that accepts an integer and returns an array. Each element of the array is a successive number between 1 and n in negabinary concatenated to itself in negaquaternary.

The negabinary representation of an integer can be computed using Schroppel's shortcut:

base(2, (i + 2863311530) $ 2863311530)


For an integer i, this is i + 2863311530, XOR 2863311530, encoded in base 2. The negaquaternary shortcut is similar:

base(4, (i + 3435973836) $ 3435973836)