A264455 Number of permutations of [n] with exactly six (possibly overlapping) occurrences of the generalized pattern 12-3.

1, 17, 238, 2956, 33343, 355182, 3681762, 37839385, 389940538, 4056942189, 42796503464, 458995025669, 5013561835833, 55832699192796, 634322118799677, 7354538207075076, 87032355679553323, 1051183375285792257, 12956782873283747998, 162950022525866642259

Offset: 5

Author

Alois P. Heinz, Nov 14 2015

Keywords

• nonn

Examples

			a(5) = 1: 12345.
a(6) = 17: 124365, 124635, 124653, 125346, 132456, 134256, 134526, 134562, 213456, 231456, 234156, 234516, 234561, 312456, 412356, 512346, 612345.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 5..500

Crossrefs

Column k=6 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, 7), polynom), j=1..o))
    end:
a:= n-> coeff(b(n, 0), x, 6):
seq(a(n), n=5..25);