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%I #16 Jul 12 2022 08:40:16
%S 0,1,6,54,792,18360,628560,29801520,1864114560,148458925440,
%T 14652778694400,1754531487878400,250496910657100800,
%U 42032247882174950400,8188505926902446745600,1832839841627736125184000,467088574163438830546944000
%N a(n) = n! * Sum_{k=1..n} k!.
%C Variant of A143217.
%H Vincenzo Librandi, <a href="/A217238/b217238.txt">Table of n, a(n) for n = 0..200</a>
%F a(n) = n!*(!(n+1) - 1).
%F a(n) = A000142(n) * A007489(n).
%t Table[n!*Sum[i!, {i, n}], {n, 0, 16}]
%o (Magma) [0] cat [Factorial(n)*&+[Factorial(k) : k in [1..n]] : n in [1..20]]; // _Wesley Ivan Hurt_, Jul 03 2020
%o (SageMath) f=factorial; [f(n)*sum(f(k) for k in (1..n)) for n in (0..40)] # _G. C. Greubel_, Jul 12 2022
%Y Cf. A000142, A007489, A061640, A143217, A217239.
%K nonn,easy
%O 0,3
%A _Olivier Gérard_, Sep 28 2012
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