OFFSET
1,1
COMMENTS
LINKS
Philippe Flajolet and Robert Sedgewick, Analytic Combinatorics, Cambridge Univ. Press, 2009, page 90.
FORMULA
G.f.: 1/( 1 - y*(1 - 1/A(x)) ) where A(x) is the o.g.f. for A002894.
EXAMPLE
4,
20, 16,
176, 160, 64,
1876, 1808, 960, 256,
22064, 22048, 13248, 5120, 1024,
275568, 282528, 182528, 83456, 25600, 4096
MATHEMATICA
nn=6; a=Sum[Binomial[2n, n]^2x^n, {n, 0, nn}]; Map[Select[#, #>0&]&, Drop[CoefficientList[Series[1/(1-y(1-1/a)), {x, 0, nn}], {x, y}], 1]]//Grid
CROSSREFS
KEYWORD
AUTHOR
Geoffrey Critzer, Oct 04 2013
STATUS
approved