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 A027301 #4 Mar 30 2012 18:56:15 %S A027301 1,2,4,13,26,100,196,820,1581,6954,13244,60214,113620,528840,990756, %T A027301 4692780,8741876,41970280,77824912,377687453,697689538,3415756084, %U A027301 6289798684,31018849628,56964451670,282658474700,517885177320 %N A027301 a(n) = self-convolution of row n of Catalan triangle (A008315). %K A027301 nonn %O A027301 0,2 %A A027301 _Clark Kimberling_