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 A027251 #8 Oct 26 2019 15:39:47
%S A027251 1,3,10,27,76,195,519,1299,3364,8311,21191,51981,131273,320715,804845,
%T A027251 1961823,4901782,11932489,29719325,72291325,179610365,436699813,
%U A027251 1082870377,2632116551,6516122403,15835522783,39147779575
%N A027251 a(n) = Sum_{k=0..n} (k+1) * A026780(n, k).
%K A027251 nonn
%O A027251 0,2
%A A027251 _Clark Kimberling_