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Search: id:A131723
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| A131723 |
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a(2n)=1-n^2, a(2n+1)=n(n+1). |
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+0
3
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| 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)
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OFFSET
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0,2
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COMMENT
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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]
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FORMULA
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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)
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CROSSREFS
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Sequence in context: A086552 A098393 A103567 this_sequence A035106 A122378 A111242
Adjacent sequences: A131720 A131721 A131722 this_sequence A131724 A131725 A131726
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KEYWORD
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sign,new
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AUTHOR
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Paul Curtz (bpcrtz(AT)free.fr), Sep 16 2007
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