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Search: id:A081405
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A081405 a(0)=a(1)=1; for n>1 a[n]=(n+1)*a(n-2) A001147 and A002866 are combed together. +0
5
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; listen)
OFFSET

0,3

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!

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

MATHEMATICA

f[x_] := (x+1)*f[x-2]; f[0]=1; f[1]=1; Table[f[w], {w, 1, 30}]

CROSSREFS

Cf. A002866, A000142, A001147.

Sequence in context: A109926 A065942 A036759 this_sequence A024858 A135100 A055486

Adjacent sequences: A081402 A081403 A081404 this_sequence A081406 A081407 A081408

KEYWORD

nonn

AUTHOR

Labos E. (labos(AT)ana.sote.hu), Apr 01 2003

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Last modified November 30 22:12 EST 2008. Contains 150989 sequences.


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