cp's OEIS Frontend

A264466 Number of permutations of [n] with exactly seven (possibly overlapping) occurrences of the generalized pattern 23-1.

%I A264466 #5 Nov 14 2015 16:55:23
%S A264466 1,111,2141,29066,336137,3663730,39037155,414003430,4414401391,
%T A264466 47606401475,521147444815,5804080039932,65854473968668,
%U A264466 761861585833395,8990938684395442,108258685340444377,1330041483208589743,16671576238569453924,213169773223813966680
%N A264466 Number of permutations of [n] with exactly seven (possibly overlapping) occurrences of the generalized pattern 23-1.
%H A264466 Alois P. Heinz, <a href="/A264466/b264466.txt">Table of n, a(n) for n = 6..500</a>
%e A264466 a(6) = 1: 456231.
%e A264466 a(7) = 111: 1567342, 2456713, 2456731, ..., 6753412, 6753421, 7456231.
%p A264466 b:= proc(u, o) option remember; `if`(u+o=0, 1, add(
%p A264466       b(u-j, o+j-1), j=1..u) +add(convert(series(
%p A264466       b(u+j-1, o-j)*x^u, x, 8), polynom), j=1..o))
%p A264466     end:
%p A264466 a:= n-> coeff(b(n, 0), x, 7):
%p A264466 seq(a(n), n=6..25);
%Y A264466 Column k=7 of A260670.
%K A264466 nonn
%O A264466 6,2
%A A264466 _Alois P. Heinz_, Nov 14 2015