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A007911 (n-1)!!-(n-2)!!. +0
2
1, 1, 5, 7, 33, 57, 279, 561, 2895, 6555, 35685, 89055, 509985, 1381905, 8294895, 24137505, 151335135, 468934515, 3061162125, 10033419375, 68000295825, 234484536825, 1645756410375, 5943863027025, 43105900812975 (list; graph; listen)
OFFSET

3,3

REFERENCES

S. P. Hurd and J. S. McCranie, Quantum factorials. Proceedings of the Twenty-fifth Southeastern International Conference on Combinatorics, Graph Theory and Computing (Boca Raton, FL, 1994). Congr. Numer. 104 (1994), 19-24.

LINKS

T. D. Noe, Table of n, a(n) for n=3..100

MAPLE

P:=proc(n) local i, j, k, w; for i from 1 by 1 to n do k:=i; w:=i-2; while w>0 do k:=k*w; w:=w-2; od; j:=i+1; w:=i-1; while w>0 do j:=j*w; w:=w-2; od; print(j-k); od; end: P(100); - Paolo P. Lava (ppl(AT)spl.at), Jun 14 2007

CROSSREFS

Cf. A007912.

Sequence in context: A090935 A153414 A104815 this_sequence A066172 A018353 A081851

Adjacent sequences: A007908 A007909 A007910 this_sequence A007912 A007913 A007914

KEYWORD

nonn,easy

AUTHOR

J. H. Conway (conway(AT)math.princeton.edu)

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Last modified November 23 17:09 EST 2009. Contains 167438 sequences.


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