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A257596 G.f.: (1-x)*(1-2*x-x^2-(1-x)*sqrt(1-2*x-3*x^2))/(2*x*(1-2*x-x^2)). 0
0, 0, 1, 3, 10, 30, 88, 252, 712, 1992, 5537, 15323, 42286, 116506, 320773, 883191, 2433112, 6709832, 18529067, 51251265, 142021430, 394336930, 1097215414, 3059549286, 8550284176, 23947824960, 67221675367, 189102714045, 533104654538 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..29.

FORMULA

D-finite with recurrence: +(n+1)*a(n) +(-5*n+1)*a(n-1) +4*(n-2)*a(n-2) +8*(n-2)*a(n-3) +(-5*n+31)*a(n-4) +3*(-n+5)*a(n-5)=0. - R. J. Mathar, Jun 12 2015

MAPLE

(1-x)*(1-2*x-x^2-(1-x)*sqrt(1-2*x-3*x^2))/(2*x*(1-2*x-x^2)) ;

taylor(%, x=0, 40) ;

gfun[seriestolist](%) ; # R. J. Mathar, Jun 12 2015

CROSSREFS

Sequence in context: A026937 A320564 A094306 * A261336 A026109 A026327

Adjacent sequences:  A257593 A257594 A257595 * A257597 A257598 A257599

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jun 04 2015

STATUS

approved

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Last modified July 24 21:47 EDT 2021. Contains 346273 sequences. (Running on oeis4.)