A061706 G.f.: x^2*(x-1)^8/(4*x^9+x^8-79*x^7+166*x^6-225*x^5+206*x^4-129*x^3+50*x^2-11*x+1).

0, 0, 1, 3, 11, 44, 185, 805, 3552, 15671, 68827, 301108, 1314553, 5735237, 25024104, 109216135, 476775195, 2081568940, 9088283129, 39679791093, 173240442512, 756351086215, 3302134987931, 14416689863220, 62941426366169

Offset: 0

Author

Vladeta Jovovic, Jun 18 2001

Keywords

• nonn

References

• R. P. Stanley, Enumerative Combinatorics I, 4.7.19.

Crossrefs

Cf. A001169.

Formula

a(n) = 11*a(n - 1) - 50*a(n - 2) + 129*a(n - 3) - 206*a(n - 4) + 225*a(n - 5) - 166*a(n - 6) + 79*a(n - 7) - a(n - 8) - 4*a(n - 9) for n >= 11.