A264467 Number of permutations of [n] with exactly eight (possibly overlapping) occurrences of the generalized pattern 23-1.

55, 1393, 22180, 290341, 3443222, 39212955, 439762906, 4922646194, 55440198721, 631281758915, 7290146619344, 85550258610256, 1021466597564828, 12418915430929303, 153814790549535203, 1941191617618161308, 24964754218212162461, 327159226788279647296

Offset: 7

Author

Alois P. Heinz, Nov 14 2015

Keywords

• nonn

Examples

			a(7) = 55: 2567341, 3456712, 3456721, ..., 6745213, 6745312, 6745321.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 7..500

Crossrefs

Column k=8 of A260670.

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^u, x, 9), polynom), j=1..o))
    end:
a:= n-> coeff(b(n, 0), x, 8):
seq(a(n), n=7..25);