A111109 Expansion of -x*(x^6+3*x^5+2*x^4-2*x^3-4*x^2+4*x-1)/((1-x)^2*(1-2*x-x^2)^2).

0, 1, 2, 5, 14, 40, 111, 301, 803, 2118, 5540, 14397, 37216, 95772, 245505, 627189, 1597413, 4057450, 10280678, 25990933, 65575122, 165138416, 415158963, 1042067549, 2611823431, 6537384302, 16342461128, 40805714573, 101776575332, 253587643300, 631232103045

Offset

0,3

Comments

The published g.f. should be multiplied by -1.

Links

Table of n, a(n) for n=0..30.

M. H. Albert and M. D. Atkinson, Simple permutations and pattern restricted permutations, Discr. Math., 300 (2005), 1-15.

Mathematica

CoefficientList[ Series[ -x*(x^6 + 3*x^5 + 2*x^4 - 2*x^3 - 4*x^2 + 4*x - 1)/((1 - x)^2*(1 - 2*x - x^2)^2), {x, 0, 30}], x] (* Robert G. Wilson v, Oct 15 2005 *)

Crossrefs

Sequence in context: A320568 A111110 A296516 * A081908 A221677 A229737

Adjacent sequences: A111106 A111107 A111108 * A111110 A111111 A111112

Keyword

nonn

Author

N. J. A. Sloane, Oct 14 2005

Status

approved