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A053817
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a(0)=1, a(n) = n*(a(n-1) + n).
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3
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1, 2, 8, 33, 148, 765, 4626, 32431, 259512, 2335689, 23356990, 256927011, 3083124276, 40080615757, 561128620794, 8416929312135, 134670868994416, 2289404772905361, 41209285912296822, 782976432333639979, 15659528646672799980, 328850101580128800021
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n)= n! + floor(2*e*n!-n) - 2, n>1. - Gary Detlefs, Jun 22 2010
E.g.f.: (1 + x * (1 + x) * exp(x)) / (1 - x). - Ilya Gutkovskiy, Oct 11 2021
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EXAMPLE
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Start with 1, add 1, multiply by 1 (getting 2), add 2, multiply by 2 (getting 8).
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MAPLE
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a:= proc(n) a(n):= n*(a(n-1) + n) end: a(0):= 1:
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MATHEMATICA
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RecurrenceTable[{a[0]==1, a[n]==n(a[n-1]+n)}, a, {n, 20}] (* Harvey P. Dale, Feb 14 2015 *)
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CROSSREFS
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KEYWORD
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nonn,easy,nice
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AUTHOR
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mindy and steve schwartz (minsteve(AT)netvision.net.il), Apr 07 2000
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EXTENSIONS
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STATUS
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approved
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