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A110043
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a(0) = 1, a(1) = 2; for n>1, a(n) = n*a(n-1) + (-1)^n.
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3
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1, 2, 5, 14, 57, 284, 1705, 11934, 95473, 859256, 8592561, 94518170, 1134218041, 14744834532, 206427683449, 3096415251734, 49542644027745, 842224948471664, 15160049072489953, 288040932377309106, 5760818647546182121, 120977191598469824540, 2661498215166336139881
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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a(n) = (n-1)*(a(n-1)+a(n-2)), n>2. - Gary Detlefs, Apr 11 2010
a(n) = 2*n! + floor((n!+1)/e) for n>0. - Gary Detlefs, Apr 11 2010
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MAPLE
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a:= proc(n) option remember;
`if`(n<2, n+1, n*a(n-1)+(-1)^n)
end:
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MATHEMATICA
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a[n_] := Subfactorial[n] + 2 Boole[n > 0] n!;
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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a(0)=1 prepended and two terms corrected by Alois P. Heinz, May 07 2020
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STATUS
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approved
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