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 A066221 #12 Apr 09 2014 09:36:11
%S A066221 0,3,25,231,2619,35695,568503,10349535,211799311,4809701439,
%T A066221 119952692895,3257843882623,95680443760575,3020676745975551,
%U A066221 101990226254706559,3666624057550245375,139813029266338603263
%N A066221 Bisection of A001189.
%H A066221 Vincenzo Librandi, <a href="/A066221/b066221.txt">Table of n, a(n) for n = 0..90</a>
%t A066221 Table[(-2)^n*HypergeometricU[-n, 3/2, -1/2] - 1, {n, 0, 16}] (* _Jean-François Alcover_, Apr 09 2014 *)
%K A066221 nonn,easy
%O A066221 0,2
%A A066221 _N. J. A. Sloane_, Dec 19 2001
%E A066221 More terms from _Sascha Kurz_, Mar 24 2002