%I #13 Oct 07 2014 16:51:27

%S 0,3,8,48,121,312,16104,122640,7596480,61171656,4093181688,

%T 2366564736720,19924948267224,12169835294351280,889585277491970400,

%U 7633882962663652968,565719454445904325272,365721616371321130128240,239498069351503974657030696,2084811062715550992506283600

%N Numbers of the form (3^k - 3)/k.

%C Generated by k: 1, 2, 3, 5, 6, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 66, 67, ...

%C Subsequence of A246445.

%e 121 is in this sequence because (3^k - 3)/k = (3^6 - 3)/6 = 121.

%Y Cf. A000040, A005935, A064535 (with form (2^k - 2)/k), A122780 (nonprimes k in a(n)), A246445, A247307 (with form (4^k - 4)/k).

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Sep 09 2014