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 A253254 #38 May 06 2022 13:13:51 %S A253254 11,5,29,19,47,7,13,37,83,23,101,13,17,5,137,73,31,41,173,13,191,23, %T A253254 19,109,227,59,7,127,263,31,281,29,23,11,317,163,67,43,353,181,53,43, %U A253254 389,199,37,47,17,31,443,113,461,53,479,61,71,23,103,131,41,271,31,7,569,17,587,149,17,307,89,79 %N A253254 Largest prime factor of the n-th 11-gonal number. %C A253254 a(A024907(n)) = A061238(n). %H A253254 Robert Israel, <a href="/A253254/b253254.txt">Table of n, a(n) for n = 2..10000</a> %F A253254 a(n) = A006530(A051682(n)). %p A253254 gpf:= n -> max(numtheory:-factorset(n)); %p A253254 seq(gpf(n*(9*n-7)/2),n=2..100); # _Robert Israel_, Jun 24 2015 %o A253254 (PARI) a(n) = my(f = factor(n*(9*n-7)/2)); f[#f~,1]; \\ _Michel Marcus_, May 31 2015 %Y A253254 Cf. A006530, A051682, A069902 (similar, with triangular numbers). %K A253254 nonn %O A253254 2,1 %A A253254 _Gionata Neri_, May 31 2015