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A141344 Expansion of (2-sqrt(1+4x))/(2-x-sqrt(1+4x)). 1
1, 1, 3, 7, 19, 45, 123, 285, 807, 1771, 5407, 10587, 37627, 57619, 279783, 231615, 2307339, -387531, 21769251, -28249347, 235837791, -539858235, 2857845723, -8509970007, 37342507167, -126289733319, 510715973643, -1837291760147 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Row sums of A141343. Hankel transform is 2^n.

Image of A052961 under the Riordan array (c(-x),xc(-x)^2), c(x) the g.f. of A000108. [From Paul Barry, Jan 29 2009]

LINKS

Table of n, a(n) for n=0..27.

FORMULA

Apparently 3*(n-1)*a(n) +2*(2*n-11)*a(n-1) +(79-31*n)*a(n-2) +2*(2*n-5)*a(n-3)=0. - R. J. Mathar, Oct 25 2012

MATHEMATICA

CoefficientList[Series[(2-Sqrt[1+4x])/(2-x-Sqrt[1+4x]), {x, 0, 30}], x] (* Harvey P. Dale, Jan 14 2013 *)

CROSSREFS

Sequence in context: A096447 A274596 A185696 * A280756 A029855 A209397

Adjacent sequences:  A141341 A141342 A141343 * A141345 A141346 A141347

KEYWORD

easy,sign

AUTHOR

Paul Barry, Jun 26 2008

STATUS

approved

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Last modified October 21 06:25 EDT 2018. Contains 316405 sequences. (Running on oeis4.)