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Search: id:A131723
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A131723 a(2n)=1-n^2, a(2n+1)=n(n+1). +0
3
0, 2, -3, 6, -8, 12, -15, 20, -24, 30, -35, 42, -48, 56, -63, 72, -80, 90, -99, 110, -120, 132 (list; graph; listen)
OFFSET

0,2

COMMENT

See A167683 for link to Hankel transform of A007325. Partial sum of signed version of A000096. [From Paul Barry (pbarry(AT)wit.ie), Nov 09 2009]

FORMULA

Contribution from Paul Barry (pbarry(AT)wit.ie), Nov 09 2009: (Start)

G.f.: x(2+x)/((1+x)^3*(1-x));

a(n)=(-1)^(n+1)(2n^2+8n+3-3(-1)^n)/8. (End)

CROSSREFS

Sequence in context: A086552 A098393 A103567 this_sequence A035106 A122378 A111242

Adjacent sequences: A131720 A131721 A131722 this_sequence A131724 A131725 A131726

KEYWORD

sign,new

AUTHOR

Paul Curtz (bpcrtz(AT)free.fr), Sep 16 2007

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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