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 A056650 #7 May 10 2013 12:44:31 %S A056650 2,7,19,127,5419,1009,9181,1423,96493,163350799,25249969, %T A056650 212520319916977,784949209969,145542538757017,147660435988297, %U A056650 2508855873622663,3565137918692593,6521735641,11273204227,16141059763,125679599753438821,240780337980146570229319,7282590063606707136764017 %N A056650 a(n) is the greatest prime factor of a(n-1)^2+a(n-1)+1. %C A056650 Except for the first term the initial (ten at least) terms are one more than a multiple of 6, with the result that a(n)^2+a(n)+1 is in these cases an odd multiple of 3 and appears to be 3 times the product of primes all of which are one more than a multiple of 6. %H A056650 Dennis Langdeau, <a href="/A056650/b056650.txt">Table of n, a(n) for n = 0..31</a> %Y A056650 Cf. A031439, A045375. %K A056650 nonn %O A056650 0,1 %A A056650 _Henry Bottomley_, Aug 09 2000 %E A056650 More terms from _Vladeta Jovovic_, Nov 26 2001