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 A217239 #20 Jul 12 2022 08:39:40
%S A217239 0,0,2,18,216,3960,110160,4399920,238412160,16777031040,1484589254400,
%T A217239 161180565638400,21054377854540800,3256459838542310400,
%U A217239 588451470350449305600,122827588903536701184000,29325437466043778002944000
%N A217239 a(n) = n!*(!n - 1) = n! * Sum_{k=1..n-1} k!.
%C A217239 Variant of A143217.
%H A217239 Vincenzo Librandi, <a href="/A217239/b217239.txt">Table of n, a(n) for n = 0..200</a>
%F A217239 a(n) = A000142(n) * A007489(n).
%F A217239 a(n) = n!*(!n - 1) = n! * Sum_{k=1..n-1} k!.
%t A217239 Table[n!*Sum[i!, {i, n-1}], {n, 0, 16}]
%o A217239 (Magma) [0,0] cat [Factorial(n)*(&+[Factorial(k): k in [1..n-1]]): n in [2..30]]; // _G. C. Greubel_, Jul 12 2022
%o A217239 (SageMath) f=factorial; [f(n)*sum(f(k) for k in (1..n-1)) for n in (0..40)] # _G. C. Greubel_, Jul 12 2022
%Y A217239 Cf. A000142, A007489, A061640, A217238.
%K A217239 nonn,easy
%O A217239 0,3
%A A217239 _Olivier Gérard_, Sep 28 2012