A264468 Number of permutations of [n] with exactly nine (possibly overlapping) occurrences of the generalized pattern 23-1.

18, 780, 15627, 235045, 3086010, 37816568, 449766437, 5291113080, 62237008779, 736806459069, 8816027319934, 106900514193980, 1315953951437664, 16464756848575162, 209528329365176670, 2713295547732215190, 35762229764646245816, 479809424452611001696

Offset

7,1

Links

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

Example

a(7) = 18: 3567241, 4567123, 4567132, 4567213, 4567312, 4567321, 4672351, 4673512, 4673521, 5671342, 5672314, 5672413, 5672431, 5673241, 5674231, 6734512, 6734521, 6745231.

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

Crossrefs

Column k=9 of A260670.

Sequence in context: A159873 A259458 A180781 * A303991 A033471 A128074

Adjacent sequences: A264465 A264466 A264467 * A264469 A264470 A264471

Keyword

nonn

Author

Alois P. Heinz, Nov 14 2015

Status

approved