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A081405
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a(0)=a(1)=1; for n>1 a[n]=(n+1)*a(n-2) A001147 and A002866 are combed together.
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4
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1, 1, 3, 4, 15, 24, 105, 192, 945, 1920, 10395, 23040, 135135, 322560, 2027025, 5160960, 34459425, 92897280, 654729075, 1857945600, 13749310575, 40874803200, 316234143225, 980995276800, 7905853580625, 25505877196800, 213458046676875
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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FORMULA
| a(0)=a(1)=1; a(2n)=A001147(2n-2) odd terms, double factorial numbers; a(2n-1)=A002866(n)=2^(n-1).n!
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MAPLE
| a[0]:=1:a[1]:=1:for n from 2 to 50 do a[n]:=(a[n-2]*(n+1)^2) od: seq(sqrt(a[n]), n=0..26); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 04 2008
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MATHEMATICA
| f[x_] := (x+1)*f[x-2]; f[0]=1; f[1]=1; Table[f[w], {w, 1, 30}]
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CROSSREFS
| Cf. A002866, A000142, A001147.
Sequence in context: A109926 A065942 A036759 * A167367 A024858 A135100
Adjacent sequences: A081402 A081403 A081404 * A081406 A081407 A081408
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Apr 01 2003
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