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 A286787 #12 May 17 2017 22:53:12
%S A286787 1,23,416,7344,134613,2620379,54636792,1223392968,29409134545,
%T A286787 757686550455,20870680635528,612964613117960,19140704352872949,
%U A286787 633710701752022635,22185391759982205904,819180275431111135536,31826528430233802890049,1298154677953792936043447,55473817874169725876166480
%N A286787 Column 2 of A286781.
%H A286787 Gheorghe Coserea, <a href="/A286787/b286787.txt">Table of n, a(n) for n = 2..211</a>
%o A286787 (PARI)
%o A286787 A286781_ser(N, t='t) = {
%o A286787 my(x='x+O('x^N), y0=1+O('x^N), y1=0, n=1);
%o A286787 while(n++,
%o A286787 y1 = (1 + x*y0 + 2*x^2*y0')*(1 - x*y0*(1-t))/(1-x*y0)^2;
%o A286787 if (y1 == y0, break()); y0 = y1;);
%o A286787 y0;
%o A286787 };
%o A286787 Kol(K,N=20) = {
%o A286787 my(s = A286781_ser(N+K, 't+O('t^(K+1))));
%o A286787 vector(N, n, polcoeff(polcoeff(s, K+n-1), K));
%o A286787 };
%o A286787 Kol(2)
%Y A286787 Cf. A286781.
%K A286787 nonn
%O A286787 2,2
%A A286787 _Gheorghe Coserea_, May 16 2017