This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A097419 #3 Mar 31 2012 14:11:11 %S A097419 2,6,66,8646,149497986,44699295486614406, %T A097419 3996054033999333969062944766851266, %U A097419 31936895685284700329548847429175178142518023225832967407199564754246 %N A097419 a(1) = 2, a(n) = 2*a(n-1)^2 - a(n-1) for n > 1. %C A097419 These numbers when factored are 2*3, 2*3*11, 2*3*11*131, 2*3*11*131*17291, 2*3*11*131*17291*298995971, 2*3*11*131*8779*10079*17291*298995971*1010341471, 2*3*11*29*59*131*241*8779*10079*17291*298995971*1010341471*2511683491*7716660340023314591, so a(n) is a prime multiple of a(n-1) for 2<=n<=6. 2,3,11,131,17291,298995971 are A090475 [Beginning with 2, a(n+1) is the least prime == -1 (mod (product a(i), i=1 to n)).] %Y A097419 Cf. A090475. %K A097419 nonn %O A097419 1,1 %A A097419 _Gerald McGarvey_, Aug 19 2004