cp's OEIS Frontend

A250210 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).

%I A250210 #14 Jun 02 2025 10:16:47
%S A250210 13,157,5,13,29,22621,7,13,19,157,659,4943,5,13,29,89,233,37,157,
%T A250210 80749,13,19141,22621,11,23,266981089,5,7,13,19,29,157,20593,477517,
%U A250210 20369233,13,211,659,4943,13063,61,157,661,9781,22621,5,13,17,29,89,97,233,260753
%N A250210 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 A250210 Triangle begins:
%e A250210 [13]
%e A250210 [157]
%e A250210 [5, 13, 29]
%e A250210 [22621]
%e A250210 [7, 13, 19, 157]
%e A250210 [659, 4943]
%e A250210 [5, 13, 29, 89, 233]
%e A250210 [37, 157, 80749]
%e A250210 [13, 19141, 22621]
%e A250210 ...
%o A250210 (PARI) tabf(nn) = for (n=1, nn, print(factor((12^n-1)/11)[,1]~);); \\ _Michel Marcus_, Dec 29 2014
%Y A250210 Cf. A102380, A004064, A250288.
%K A250210 nonn,tabf
%O A250210 2,1
%A A250210 _Eric Chen_, Dec 29 2014