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A114633
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a(n) = (n+1)*(n+2)/2*sum(k=0,floor(n/2),n!/(n-2*k)! ).
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0
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1, 3, 18, 70, 555, 2961, 31108, 213228, 2799765, 23455135, 369569046, 3659001138, 67261566463, 768390239085, 16142775951240, 209002145031256, 4939689441079593, 71478733600689723
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Formula were found by Paul D. Hanna. Related to logarithmic numbers A002104.
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FORMULA
| a(n) = A087208(n)*(n+1)*(n+2)/2 (Hanna)
G.f.: exp(x)/(1-x^2)*(x^2/2). [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 03 2009]
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MAPLE
| a := n -> (n+1)*(n+2)/2*sum(n!/(n-2*k)!, k=0..floor(n/2));
restart: G(x):=exp(x)/(1-x^2)*(x^2/2): f[0]:=G(x): for n from 1 to 29 do f[n]:=diff(f[n-1], x) od: x:=0: seq(f[n], n=2..19); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 03 2009]
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CROSSREFS
| Cf. A087208, A002104.
Sequence in context: A157535 A098522 A174764 * A135070 A073961 A152897
Adjacent sequences: A114630 A114631 A114632 * A114634 A114635 A114636
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KEYWORD
| nonn
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AUTHOR
| Creighton Dement (creighton.k.dement(AT)uni-oldenburg.de), Feb 17 2006
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