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A217238
a(n) = n! * Sum_{k=1..n} k!.
3
0, 1, 6, 54, 792, 18360, 628560, 29801520, 1864114560, 148458925440, 14652778694400, 1754531487878400, 250496910657100800, 42032247882174950400, 8188505926902446745600, 1832839841627736125184000, 467088574163438830546944000
OFFSET
0,3
COMMENTS
Variant of A143217.
LINKS
FORMULA
a(n) = n!*(!(n+1) - 1).
a(n) = A000142(n) * A007489(n).
MATHEMATICA
Table[n!*Sum[i!, {i, n}], {n, 0, 16}]
PROG
(Magma) [0] cat [Factorial(n)*&+[Factorial(k) : k in [1..n]] : n in [1..20]]; // Wesley Ivan Hurt, Jul 03 2020
(SageMath) f=factorial; [f(n)*sum(f(k) for k in (1..n)) for n in (0..40)] # G. C. Greubel, Jul 12 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Olivier Gérard, Sep 28 2012
STATUS
approved