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 A027243 #9 Oct 26 2019 16:17:03
%S A027243 1,3,8,22,55,143,349,885,2138,5356,12890,32092,77178,191530,460934,
%T A027243 1141888,2751551,6809421,16431189,40633227,98175341,242626935,
%U A027243 586867463,1449457735,3509084995,8661201115,20982916461,51755457003
%N A027243 a(n) = Sum_{k=0..n} (k+1) * A026769(n, k).
%K A027243 nonn
%O A027243 0,2
%A A027243 _Clark Kimberling_