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 A049426 #28 Jan 18 2025 09:05:48
%S A049426 1,1,4,16,76,436,2776,19384,148576,1226656,10824256,101695936,
%T A049426 1010783104,10577428096,116166090496,1334409569536,15985101216256,
%U A049426 199216504113664,2577292524107776,34542575915216896,478781761481291776
%N A049426 Row sums of triangle A049410.
%H A049426 Seiichi Manyama, <a href="/A049426/b049426.txt">Table of n, a(n) for n = 0..547</a>
%H A049426 W. Lang, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL3/LANG/lang.html">On generalizations of Stirling number triangles</a>, J. Integer Seqs., Vol. 3 (2000), #00.2.4.
%F A049426 E.g.f.: exp((-1+(1+x)^4)/4).
%F A049426 a(n) = n!*Sum_(k=1..n, Sum_(j=0..k, binomial(4*j,n)*(-1)^(k-j)/(4^k*(k-j)!*j!))). - _Vladimir Kruchinin_, Feb 07 2011
%F A049426 D-finite with recurrence a(n) -a(n-1) +3*(-n+1)*a(n-2) -3*(n-1)*(n-2)*a(n-3) -(n-1)*(n-2)*(n-3)*a(n-4)=0. - _R. J. Mathar_, Jun 23 2023
%F A049426 a(n) = Sum_{k=0..n} Stirling1(n,k) * A004213(k). - _Seiichi Manyama_, Jan 31 2024
%F A049426 a(n) = (1/exp(1/4)) * n! * Sum_{k>=0} binomial(4*k,n)/(4^k * k!). - _Seiichi Manyama_, Jan 18 2025
%t A049426 With[{nn=20},CoefficientList[Series[Exp[((1+x)^4-1)/4],{x,0,nn}],x] Range[ 0,nn]!] (* _Harvey P. Dale_, Jan 28 2017 *)
%Y A049426 Cf. A004213, A049410.
%Y A049426 Column of A293991.
%K A049426 easy,nonn
%O A049426 0,3
%A A049426 _Wolfdieter Lang_