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A106181 Expansion of c(-x^2)(1+2x-sqrt(1+4x^2))/2, c(x) the g.f. of A000108. 4
0, 1, -1, -1, 2, 2, -5, -5, 14, 14, -42, -42, 132, 132, -429, -429, 1430, 1430, -4862, -4862, 16796, 16796, -58786, -58786, 208012, 208012, -742900, -742900, 2674440, 2674440, -9694845, -9694845, 35357670, 35357670, -129644790, -129644790, 477638700, 477638700, -1767263190, -1767263190 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

Second column of number triangle A106180.

LINKS

Table of n, a(n) for n=0..39.

FORMULA

a(n)=sin(pi*n/2)(C((n-1)/2)(1-(-1)^n)/2)+sin(pi*(n+1)/2)(C(n/2)(1+(-1)^n)/2)-0^n.

Conjecture: (n+2)*a(n) +n*a(n-1)+ 4*(n-1)*a(n-2) +4*(n-3)*a(n-3)=0. - R. J. Mathar, Nov 15 2011

CROSSREFS

Cf. A099363.

Sequence in context: A129996 A208355 A099363 * A098887 A259097 A245845

Adjacent sequences:  A106178 A106179 A106180 * A106182 A106183 A106184

KEYWORD

easy,sign

AUTHOR

Paul Barry, Apr 24 2005

STATUS

approved

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Last modified October 21 08:42 EDT 2018. Contains 316405 sequences. (Running on oeis4.)