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 A349270 #14 Aug 02 2023 09:38:05
%S A349270 1,2,5,16,46,204,986,6400,48094,420140,4112822,44575584,528787260,
%T A349270 6811260792,94637153172,1410542965248,22446384533142,379801729831500,
%U A349270 6808478318116238,128895044005636960,2569653423591937156,53808349548318974312,1180737041228428129580
%N A349270 a(n) = Sum_{k=0..n} (n - k)! * k! / floor(k / 2)!^2, row sums of A349269.
%H A349270 Seiichi Manyama, <a href="/A349270/b349270.txt">Table of n, a(n) for n = 0..449</a>
%t A349270 Table[Sum[(n-k)! k! / Floor[k/2]!^2,{k,0,n}],{n,0,22}] (* _Stefano Spezia_, Nov 13 2021 *)
%o A349270 (PARI) a(n) = sum(k=0, n, (n - k)!*k!/(k\2)!^2); \\ _Michel Marcus_, Nov 13 2021
%Y A349270 Cf. A349269.
%K A349270 nonn
%O A349270 0,2
%A A349270 _Peter Luschny_, Nov 13 2021