A014850 Numbers k that divide s(k), where s(1)=1, s(j)=3*s(j-1)+j.

1, 3, 39, 507, 6591, 12207, 85683, 158691, 255567, 285987, 1028703, 1113879, 2062983, 3322371, 3717831, 3820791, 13373139, 14480427, 26818779, 31089279, 43190823, 48331803, 49670283, 79992471, 89513931, 173850807, 188245551, 321984039, 348644127, 404160627, 561480699, 628313439, 645713679

Offset: 1

Author

N. J. A. Sloane, Olivier Gérard

Keywords

• nonn

Examples

			39 is in the sequence as A000340(39-1) = 3039416364764232180 is divisible by 39. - _David A. Corneth_, Aug 08 2021
		

Crossrefs

s(n) = A000340(n-1).

Programs

PARI

lista(nn) = my(s); for(k=1, nn, s=3*s+k; if(s%k==0, print1(k, ", "))); \\ Jinyuan Wang, Aug 08 2021

PARI

is(n) = n%2==1 && lift(Mod(3, n)^(n + 1) - Mod(3, n)) == 0 \\ David A. Corneth, Aug 08 2021

Extensions

a(7)-a(16) from Arkadiusz Wesolowski, Jul 03 2011

More terms from David A. Corneth, Aug 08 2021