A250210 - OEIS

%I #12 Dec 29 2014 08:24:25

%S 13,157,5,13,29,22621,7,13,19,157,659,4943,5,13,29,89,233,37,157,

%T 80749,13,19141,22621,11,23,266981089,5,7,13,19,29,157,20593,477517,

%U 20369233,13,211,659,4943,13063,61,157,661,9781,22621,5,13,17,29,89,97,233,260753

%N Irregular triangle read by rows in which row n lists the prime factors of the duodecimal repunit ((12^n-1)/11). (Written in base 10)

%e Triangle begins:

%e [13]

%e [157]

%e [5, 13, 29]

%e [22621]

%e [7, 13, 19, 157]

%e [659, 4943]

%e [5, 13, 29, 89, 233]

%e [37, 157, 80749]

%e [13, 19141, 22621]

%e ...

%o (PARI) tabf(nn) = for (n=1, nn, print(factor((12^n-1)/11)[,1]~);); \\ _Michel Marcus_, Dec 29 2014

%Y Cf. A102380, A004064, A250288.

%K nonn,tabf

%O 2,1

%A _Eric Chen_, Dec 29 2014