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A127630 Expansion of (1+x-x^2-x^3)/(1+x^2)^2. +0
2
1, 1, -3, -3, 5, 5, -7, -7, 9, 9, -11, -11, 13, 13, -15, -15, 17, 17, -19, -19, 21, 21, -23, -23, 25, 25, -27, -27, 29, 29, -31, -31, 33, 33, -35, -35, 37, 37, -39, -39, 41, 41, -43, -43, 45, 45, -47, -47, 49, 49, -51, -51, 53, 53, -55, -55 (list; graph; listen)
OFFSET

0,3

COMMENT

Hankel transform of A045621(n+1).

FORMULA

a(n)=(2^C(n,2))*(2*floor(n/2)+1)

CROSSREFS

Cf. A109613.

Sequence in context: A133909 A117767 A063196 this_sequence A109613 A073737 A133908

Adjacent sequences: A127627 A127628 A127629 this_sequence A127631 A127632 A127633

KEYWORD

easy,sign

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Jan 20 2007

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Last modified November 24 23:16 EST 2009. Contains 167481 sequences.


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