A276989 Reversion of x - x^2 - x^6.

1, 1, 2, 5, 14, 43, 140, 474, 1650, 5863, 21170, 77441, 286372, 1068790, 4020704, 15230470, 58044354, 222401745, 856235030, 3310615055, 12849946406, 50051007940, 195571906140, 766413504375, 3011469930300, 11862075827007, 46830440626612, 185271557066226

Offset

1,3

Links

Table of n, a(n) for n=1..28.

Vladimir Kruchinin, The method for obtaining expressions for coefficients of reverse generating functions, arXiv:1211.3244 [math.CO], 2012.

Formula

a(n) = (Sum_{j=0..(n-1)/2} C(n-1-4*j,j)*C(2*n-4*j-2,n-1))/n.

Mathematica

Table[Sum[Binomial[n-1-4*j, j]Binomial[2*n-4*j-2, n-1], {j, 0, (n-1)/2}]/n, {n, 1, 25}]

Crossrefs

Sequence in context: A149880 A066351 A181496 * A272461 A213264 A029889

Adjacent sequences: A276986 A276987 A276988 * A276990 A276991 A276992

Keyword

nonn

Author

Benedict W. J. Irwin, Sep 24 2016

Status

approved