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A108869
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E.g.f. : exp(6x)/(1-x).
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2
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1, 7, 50, 366, 2760, 21576, 176112, 1512720, 13781376, 134110080, 1401566976, 15780033792, 191537187840, 2503044135936, 35120982067200, 527284915992576, 8439379765788672, 143486382677852160, 2582856448158007296
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OFFSET
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0,2
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COMMENTS
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a(n) is the permanent of the n X n matrix with 7's on the diagonal and 1's elsewhere.
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LINKS
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FORMULA
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a(n) = n!*Sum_{ k = 0..n } 6^k/k!.
a(n) = Sum_{ k = 0..n } A008290(n, k)*7^k.
a(n) Sum_{ k = 0..n } k!*C(n, k)*6^(n-k).
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MAPLE
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a:=n->n!*sum(6^k/k!, k=0..n): seq(a(n), n=0..20); # Emeric Deutsch, Jul 18 2005
restart:F(x):=exp(6*x)/(1-x): f[0]:=F(x): for n from 1 to 20 do f[n]:=diff(f[n-1], x) od: x:=0: seq(f[n], n=0..18); # Zerinvary Lajos, Apr 03 2009
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MATHEMATICA
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a[n_] := n! * Sum[6^k/k!, {k, 0, n}]; Array[a, 19, 0] (* Amiram Eldar, Jun 30 2020 *)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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