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 A027249 #9 Oct 26 2019 15:36:39
%S A027249 1,9,59,338,1937,10289,57345,299832,1663421,8705069,48391863,
%T A027249 254818488,1421911953,7544528179,42264280735,225949128338,
%U A027249 1270219491983,6838142459779,38557301241769,208865221891584,1180647902778713,6430734346787925,36426544777112515,199364753897943071
%N A027249 a(n) = Sum_{k=0..n-2} T(n,k) * T(n,k+2), with T given by A026780.
%K A027249 nonn
%O A027249 2,2
%A A027249 _Clark Kimberling_
%E A027249 More terms from _Sean A. Irvine_, Oct 26 2019