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A131723 a(2*n) = 1-n^2, a(2*n+1) = n*(n+1). 4
0, 2, -3, 6, -8, 12, -15, 20, -24, 30, -35, 42, -48, 56, -63, 72, -80, 90, -99, 110, -120, 132, -143, 156, -168, 182, -195, 210, -224, 240, -255, 272, -288, 306, -323, 342, -360, 380, -399, 420, -440, 462, -483, 506, -528, 552, -575, 600, -624, 650, -675 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

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

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..10000

FORMULA

From Paul Barry, Nov 09 2009: (Start)

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

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

PROG

(MAGMA) [(-1)^(n+1)*(2*n^2+8*n+3-3*(-1)^n)/8: n in [0..50]]; // Vincenzo Librandi, Aug 10 2011

CROSSREFS

Sequence in context: A086552 A098393 A103567 * A198442 A035106 A122378

Adjacent sequences:  A131720 A131721 A131722 * A131724 A131725 A131726

KEYWORD

sign

AUTHOR

Paul Curtz, Sep 16 2007

EXTENSIONS

More terms from Vincenzo Librandi, Aug 10 2011

STATUS

approved

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Last modified November 24 07:22 EST 2014. Contains 249872 sequences.