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A128214 Expansion of (1+2x+3x^2)/(1+x+x^2)^2. +0
2
1, 0, 0, -2, 3, 0, -5, 6, 0, -8, 9, 0, -11, 12, 0, -14, 15, 0, -17, 18, 0, -20, 21, 0, -23, 24, 0, -26, 27, 0, -29, 30, 0, -32, 33, 0, -35, 36, 0, -38, 39, 0, -41, 42, 0, -44, 45, 0, -47, 48, 0, -50, 51, 0, -53, 54 (list; graph; listen)
OFFSET

0,4

COMMENT

Binomial transform is A128213.

FORMULA

a(n)=(1-n)cos(2*pi*n/3)+(n-1)*sin(2*pi*n/3)/sqrt(3)

CROSSREFS

Adjacent sequences: A128211 A128212 A128213 this_sequence A128215 A128216 A128217

Sequence in context: A057637 A140508 A063956 this_sequence A145105 A140700 A055615

KEYWORD

easy,sign

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Feb 19 2007

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Last modified November 7 16:45 EST 2009. Contains 166093 sequences.


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