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 A258766 Fixed points in A256271. 2
 1, 2, 3, 26, 32, 34, 37, 49, 55, 62, 64, 74, 75, 76, 77, 164, 171, 189, 224, 273, 279, 280, 285, 303, 333, 345, 356, 363, 368, 382, 399, 411, 416, 422, 429, 430, 435, 441, 453, 470, 472, 483, 494, 524, 539, 561, 566, 579, 580, 585, 603, 609, 621, 644, 662, 666, 674, 693, 704, 715, 737, 771, 777, 794, 803 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Numbers n such that A256271(n) = n. From Robert Israel, Jul 16 2019: (Start) A necessary condition for n to be in the sequence is that A256271(n)-n is even. When A256271(n) is even, A256271(n+1) must be odd; when A256271(n) is odd, A256721(n+1) may be either even or odd, but it appears that it is nearly always even. The result is that we have long intervals where A256721(n)-n is even (e.g. 3369 to 22635), in which members of this sequence are relatively common, and long intervals where A256721(n)-n is odd (e.g. 22636 to 67110) which contain no members of this sequence. (End) LINKS Robert Israel, Table of n, a(n) for n = 1..1000 MAPLE Res:= 1: count:= 1: v:= 1: Cands:= [\$2..1000]: for n from 2 do found:= false; for j from 1 to nops(Cands) do if numtheory:-issqrfree(v + Cands[j]^2) then found:= true; if n = Cands[j] then Res:= Res, n; count:= count+1 fi; v:= Cands[j]^2; Cands:= subsop(j=NULL, Cands); break fi od; if not found then break fi; od: Res; # Robert Israel, Jul 16 2019 PROG (PARI) print1(1, ", "); v=[1]; n=1; while(#v<10^3, if(issquarefree(n^2+v[#v]^2)&&!vecsearch(vecsort(v), n), if(n==#v, print1(n, ", ")); n=0); n++) CROSSREFS Cf. A121878, A167906, A256271. Sequence in context: A041659 A042043 A178196 * A056722 A181225 A143876 Adjacent sequences: A258763 A258764 A258765 * A258767 A258768 A258769 KEYWORD nonn,look AUTHOR Derek Orr, Jun 09 2015 STATUS approved

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Last modified June 13 17:32 EDT 2024. Contains 373391 sequences. (Running on oeis4.)
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