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 A026890 #4 Mar 30 2012 18:56:11 %S A026890 1,9,56,301,1506,7258,34322,161039,755145,3556269,16876326,80881483, %T A026890 392014244,1922785012,9545380884,47947476888,243553779646, %U A026890 1250097073918,6477850149236,33857970839030,178339124650000,945852940569120 %N A026890 T(2n+1,n+4), T given by A026769. %K A026890 nonn %O A026890 3,2 %A A026890 _Clark Kimberling_