A014851 Numbers k that divide s(k), where s(1)=1, s(j)=4*s(j-1)+j.

1, 2, 3, 4, 6, 9, 10, 12, 18, 20, 21, 27, 30, 36, 42, 50, 54, 60, 63, 68, 78, 81, 84, 90, 100, 108, 110, 126, 147, 150, 156, 162, 171, 180, 189, 204, 210, 220, 234, 243, 250, 252, 270, 294, 300, 310, 324, 330, 340, 342, 378, 390, 410, 420, 441, 450, 468, 486

Offset: 1

Author

N. J. A. Sloane, Olivier Gérard

Keywords

• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

s(n) = A014825(n).

Programs

Mathematica

nxt[{k_,a_}]:={k+1,4a+k+1}; Transpose[Select[NestList[nxt,{1,1},500], Divisible[#[[2]],#[[1]]]&]][[1]] (* Harvey P. Dale, May 29 2013 *)