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 A195394 #21 Aug 05 2025 10:21:58
%S A195394 1,3628800,2432902008176640000,265252859812191058636308480000000,
%T A195394 815915283247897734345611269596115894272000000000,
%U A195394 30414093201713378043612608166064768844377641568960512000000000000
%N A195394 a(n) = (10*n)!
%F A195394 From _Amiram Eldar_, Apr 03 2021: (Start)
%F A195394 a(n) = A000142(A008592(n)).
%F A195394 Sum_{n>=0} 1/a(n) = A195070.
%F A195394 Sum_{n>=0} (-1)^n/a(n) = A196498. (End)
%t A195394 a[n_] := (10*n)!; Array[a, 6, 0] (* _Amiram Eldar_, Apr 03 2021 *)
%t A195394 (10*Range[0,10])! (* _Harvey P. Dale_, Aug 04 2025 *)
%o A195394 (Magma) [Factorial(10*n): n in [0..10]];
%Y A195394 Cf. A000142, A008592, A010050, A100732, A100733, A100734, A195390, A195391, A195392, A195393.
%Y A195394 Cf. A195070, A196498.
%K A195394 nonn,easy
%O A195394 0,2
%A A195394 _Vincenzo Librandi_, Sep 24 2011