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 A064338 #13 Feb 06 2023 07:56:50
%S A064338 1,2,3,3,3,4,-6,49,-178,76,8633,-124131,1202662,-8252662,16009623,
%T A064338 730544913,-17236420029,256679586178,-2787185606474,15947981601793,
%U A064338 215110909342463,-9723413157539188,216257810122284716,-3515999949642686709
%N A064338 Row sums of signed triangle A064334.
%H A064338 Robert Israel, <a href="/A064338/b064338.txt">Table of n, a(n) for n = 0..488</a>
%F A064338 a(n) = 1 + Sum_{0<=k<=n-1} hypergeom([1-n+k,n-k],[-n+k],-k). - _Robert Israel_, Jan 03 2019
%p A064338 f:= proc(n) local k; 1 + add(simplify(hypergeom([1-n+k,n-k],[-n+k],-k)),k=0..n-1) end proc:
%p A064338 map(f, [$0..50]); # _Robert Israel_, Jan 03 2019
%t A064338 a[n_] := If[n == 0, 1, Sum[(n-k-j)*Binomial[n-k-1+j, j]* (-k)^j/(n-k), {k, 1, n-1}, {j, 0, n-k-1}] + 2];
%t A064338 Table[a[n], {n, 0, 50}] (* _Jean-François Alcover_, Feb 06 2023 *)
%Y A064338 Cf. A064339 (row sums of unsigned triangle A064334).
%K A064338 sign
%O A064338 0,2
%A A064338 _Wolfdieter Lang_, Sep 21 2001