A264464 Number of permutations of [n] with exactly five (possibly overlapping) occurrences of the generalized pattern 23-1.

22, 392, 4302, 41979, 393476, 3652779, 34099448, 322746351, 3111556310, 30637025849, 308542096284, 3180677263083, 33574281993047, 362907367462521, 4016295885663247, 45496983534864142, 527373693673894161, 6252643277063017082, 75794122449729562363

Offset: 6

Author

Alois P. Heinz, Nov 14 2015

Keywords

• nonn

Examples

			a(6) = 22: 245613, 245631, 256341, 345261, 346251, 356124, 356142, 356214, 356412, 356421, 452361, 453612, 453621, 462351, 463512, 463521, 561342, 562314, 562413, 562431, 563241, 564231.
		

Links

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

Crossrefs

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