A263888 Number of permutations of [n] containing exactly four occurrences of the consecutive pattern 132.

105, 7968, 306729, 8862336, 221041785, 5090751360, 112456455285, 2438635714560, 52685573396310, 1145097655557120, 25201633254603750, 564111809386352640, 12881077471698335550, 300654388617807974400, 7182803417002318476630, 175794354355113443819520

Offset: 9

Author

Alois P. Heinz, Oct 28 2015

Keywords

• nonn

Examples

			a(9) = 105: 132547698, 132548697, 132549687, ..., 192835476, 192836475, 192837465.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 9..100

Crossrefs

Column k=4 of A197365.

Programs

Maple

b:= proc(u, o, t) option remember; series(`if`(u+o=0, 1,
      add(b(u-j, o+j-1, 0)*`if`(j<=t, x, 1), j=1..u)+
      add(b(u+j-1, o-j, j-1), j=1..o)), x, 5)
    end:
a:= n-> coeff(b(n, 0$2), x, 4):
seq(a(n), n=9..35);

Formula

a(n) = A197365(n,4).