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A056199
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A simple recurrence.
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3
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0, 1, 3, 11, 51, 291, 1971, 15411, 136371, 1345971, 14651571, 174318771, 2249992371, 31309422771, 467200878771, 7441464174771, 126003940206771, 2260128508782771, 42808495311726771, 853775831370606771
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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FORMULA
| a(1)=0, a(2)=1, a(n) = n * a(n-1) - Sum_{k=1..n-2} a(k).
a(1)=0, n>1 a(n)=(1/3)*(-1+sum(k=0, n, k!)) - Benoit Cloitre (benoit7848c(AT)orange.fr), Nov 12 2005
a(n)=A007489(n)/3 for n>=2 . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Feb 10 2007
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MATHEMATICA
| a[1]=0; a[2]=1; a[n_Integer] := n*a[n-1]-Sum[a[k], {k, 1, n-2}]; Table[a[n], {n, 1, 22}]
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CROSSREFS
| Cf. A003422.
Sequence in context: A020043 A184819 A113712 * A007047 A129097 A179322
Adjacent sequences: A056196 A056197 A056198 * A056200 A056201 A056202
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KEYWORD
| easy,nonn
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Sept 26, 1996.
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