A014850 - OEIS

%I #28 Aug 09 2021 12:25:21

%S 1,3,39,507,6591,12207,85683,158691,255567,285987,1028703,1113879,

%T 2062983,3322371,3717831,3820791,13373139,14480427,26818779,31089279,

%U 43190823,48331803,49670283,79992471,89513931,173850807,188245551,321984039,348644127,404160627,561480699,628313439,645713679

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

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

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

%o (PARI) is(n) = n%2==1 && lift(Mod(3, n)^(n + 1) - Mod(3, n)) == 0 \\ _David A. Corneth_, Aug 08 2021

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

%K nonn

%O 1,2

%A _N. J. A. Sloane_, _Olivier Gérard_

%E a(7)-a(16) from _Arkadiusz Wesolowski_, Jul 03 2011

%E More terms from _David A. Corneth_, Aug 08 2021