OFFSET
0,4
COMMENTS
Hankel transform is (-1)^n. - Paul Barry, Jun 17 2010
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
FORMULA
G.f.: A(x) = 2/(3+3*x - sqrt(1+6*x+5*x^2)). - Paul D. Hanna, Feb 23 2004
Conjecture: 2*n*a(n) + (13*n-16)*a(n-1) + 4*(4*n-7)*a(n-2) + 5*(n-2)*a(n-3) = 0. - R. J. Mathar, Nov 24 2012
a(n) ~ (-1)^(n+1) * 5^(n+3/2) / (72 * sqrt(Pi) * n^(3/2)). - Vaclav Kotesovec, Feb 12 2014
MATHEMATICA
CoefficientList[Series[2/(3+3*x-Sqrt[1+6*x+5*x^2]), {x, 0, 20}], x] (* Vaclav Kotesovec, Feb 12 2014 *)
PROG
(PARI) a(n)=polcoeff(2/(3+3*x-sqrt(1+6*x+5*x^2+x*O(x^n))), n, x) \\ Paul D. Hanna
CROSSREFS
KEYWORD
sign
AUTHOR
Christian G. Bower, Jan 29 2004
STATUS
approved