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A135863 G.f. A(x) = 1 + 4x*A(x)^(1/2) ; A(x) = 1 + 8x^2 + 4x*sqrt(1 + 4x^2). 3
1, 4, 8, 8, 0, -8, 0, 16, 0, -40, 0, 112, 0, -336, 0, 1056, 0, -3432, 0, 11440, 0, -38896, 0, 134368, 0, -470288, 0, 1664096, 0, -5943200, 0, 21395520, 0, -77558760, 0, 282861360, 0, -1037158320, 0, 3821109600, 0, -14138105520, 0, 52512963360, 0, -195730136160 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..45.

FORMULA

a(n) = -4^n*binomial(n/2,n)/(n/2 - 1), except a(2) = 8, for n>=0.

G.f.: (exp(asinh(2*x)))^2. - Philippe Deléham, Feb 01 2012

PROG

(PARI) a(n)=4^n*if(n==2, 1/2, binomial(n/2, n)/(1-n/2))

CROSSREFS

Cf. A135864, A000108.

Sequence in context: A196282 A196332 A245654 * A176221 A021676 A122153

Adjacent sequences:  A135860 A135861 A135862 * A135864 A135865 A135866

KEYWORD

sign

AUTHOR

Paul D. Hanna, Dec 02 2007

STATUS

approved

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Last modified September 21 21:15 EDT 2019. Contains 327282 sequences. (Running on oeis4.)