A264458 Number of permutations of [n] with exactly nine (possibly overlapping) occurrences of the generalized pattern 12-3.

1, 39, 859, 14531, 211877, 2822490, 35642278, 437300537, 5296987965, 63998700926, 776411239316, 9499309138937, 117556007163447, 1474385436584002, 18766076242349261, 242618101536221884, 3187985361564230544, 42590476320847716703, 578630818810648513246

Offset: 6

Author

Alois P. Heinz, Nov 14 2015

Keywords

• nonn

Examples

			a(6) = 1: 123465.
a(7) = 39: 1237465, 1237546, 1237564, ..., 5123476, 6123475, 7123465.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 6..500

Crossrefs

Column k=9 of A260665.

Programs

Maple

b:= proc(u, o) option remember; `if`(u+o=0, 1, add(
       b(u-j, o+j-1), j=1..u)+add(convert(series(
       b(u+j-1, o-j)*x^(o-j), x, 10), polynom), j=1..o))
    end:
a:= n-> coeff(b(n, 0), x, 9):
seq(a(n), n=6..25);