cp's OEIS Frontend

A264458 Number of permutations of [n] with exactly nine (possibly overlapping) occurrences of the generalized pattern 12-3.

%I A264458 #6 Nov 14 2015 08:17:21
%S A264458 1,39,859,14531,211877,2822490,35642278,437300537,5296987965,
%T A264458 63998700926,776411239316,9499309138937,117556007163447,
%U A264458 1474385436584002,18766076242349261,242618101536221884,3187985361564230544,42590476320847716703,578630818810648513246
%N A264458 Number of permutations of [n] with exactly nine (possibly overlapping) occurrences of the generalized pattern 12-3.
%H A264458 Alois P. Heinz, <a href="/A264458/b264458.txt">Table of n, a(n) for n = 6..500</a>
%e A264458 a(6) = 1: 123465.
%e A264458 a(7) = 39: 1237465, 1237546, 1237564, ..., 5123476, 6123475, 7123465.
%p A264458 b:= proc(u, o) option remember; `if`(u+o=0, 1, add(
%p A264458        b(u-j, o+j-1), j=1..u)+add(convert(series(
%p A264458        b(u+j-1, o-j)*x^(o-j), x, 10), polynom), j=1..o))
%p A264458     end:
%p A264458 a:= n-> coeff(b(n, 0), x, 9):
%p A264458 seq(a(n), n=6..25);
%Y A264458 Column k=9 of A260665.
%K A264458 nonn
%O A264458 6,2
%A A264458 _Alois P. Heinz_, Nov 14 2015