OFFSET
0,2
LINKS
Youngja Park and SeungKyung Park, Enumeration of generalized lattice paths by string types, peaks, and ascents, Discrete Mathematics 339.11 (2016): 2652-2659.
FORMULA
G.f.: 1/((1-8*x)*sqrt(1-8*x)) = 1F0(3/2;;8x).
a(n) = Jacobi_P(n,1/2,1/2,1)*8^n.
a(n) = 2^n*(2*n+1)*binomial(2*n,n).
a(n) = (2*n+1)*A059304(n).
a(n) = 2^n*A002457(n).
D-finite with recurrence: n*a(n) -4*(2*n+1)*a(n-1) =0. - R. J. Mathar, Nov 14 2011
G.f.: G(0)/2, where G(k) = 1 + 1/(1 - 8*x*(2*k+3)/(8*x*(2*k+3) + 2*(k+1)/G(k+1))); (continued fraction). - Sergei N. Gladkovskii, Jun 06 2013
Sum_{n>=0} (-1)^n/a(n) = 4/3*log(2). - Daniel Suteu, Oct 31 2017
Sum_{n>=0} 1/a(n) = 8*arcsin(1/sqrt(8))/sqrt(7). - Amiram Eldar, Jan 27 2024
MAPLE
a:= n-> add((binomial(2*n, n))*2^(n-2), j=1..n): seq(a(n), n=1..20); # Zerinvary Lajos, May 03 2007
MATHEMATICA
CoefficientList[Series[(1-8x)^-(3/2), {x, 0, 30}], x] (* Harvey P. Dale, Jul 13 2012 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Feb 02 2006
STATUS
approved