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 A027212 #12 Oct 25 2019 16:52:43
%S A027212 1,3,8,23,55,144,328,816,1808,4358,9485,22377,48097,111720,237917,
%T A027212 546161,1154827,2626624,5522464,12467540,26092324,58546544,122059348,
%U A027212 272479782,566242186,1258568324,2608232758,5775620396,11940756076
%N A027212 a(n) = Sum_{k=0..n} (k+1) * A026725(n, n-k).
%p A027212 A027212 := proc(n)
%p A027212 add( (k+1)*A026725(n,n-k),k=0..n) ;
%p A027212 end proc: # _R. J. Mathar_, Oct 21 2019
%K A027212 nonn
%O A027212 0,2
%A A027212 _Clark Kimberling_
%E A027212 Name corrected by _R. J. Mathar_, Oct 21 2019