A353069 Positions k such that A097465(k) and A097465(k+1) are odd.

1, 2, 7, 12, 41, 100, 521, 1150, 10391, 15008, 255247, 1786778, 4849835, 5870858, 6561553, 557732162, 3234846601, 3457939474, 4360010651

Offset

1,2

Comments

Fixed points in A097465 appear in the intervals [12, 41], [100, 521], [1150, 10391], etc.

Links

Table of n, a(n) for n=1..19.

Rémy Sigrist, C program

Mathematica

nn = 2^20; c = {1}; j = 1; u = 2; {1}~Join~Reap[Do[k = u; While[Nand[FreeQ[c, k], CoprimeQ[j, k], k != j + 1, k != j - 1], k++]; j = k; AppendTo[c, k]; If[# != s, s = #; Sow[i - 1]] &@ Mod[#, 2] &@ Abs[k - i]; If[k == u, While[MemberQ[c, u], u++]; c = DeleteCases[c, _?(# < u &)]], {i, 2, nn}]][[-1, -1]]

Prog

(C) See Links section.

Crossrefs

Cf. A097465, A351646, A352096.

Sequence in context: A238366 A084068 A192772 * A046243 A230302 A230637

Adjacent sequences: A353066 A353067 A353068 * A353070 A353071 A353072

Keyword

nonn,more

Author

Michael De Vlieger, May 05 2022

Extensions

a(17)-a(19) from Rémy Sigrist, May 07 2022

Status

approved