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A317287 Number of permutations of [n] with exactly seven increasing runs of even length. 2

%I

%S 199360981,11190963430,378291607803,11014069796526,305943708449074,

%T 8211684416287224,215906484804391566,5654455021954104792,

%U 148657867362265421769,3937297418900898841450,105451222548147683308147,2864250745636538809593802,79027581972356621300952774

%N Number of permutations of [n] with exactly seven increasing runs of even length.

%H Alois P. Heinz, <a href="/A317287/b317287.txt">Table of n, a(n) for n = 14..469</a>

%p b:= proc(u, o, t) option remember; series(`if`(u+o=0, x^t,

%p add(b(u+j-1, o-j, irem(t+1, 2)), j=1..o)+

%p add(b(u-j, o+j-1, 0)*x^t, j=1..u)), x, 8)

%p end:

%p a:= n-> coeff(b(n, 0$2), x, 7):

%p seq(a(n), n=14..30);

%Y Column k=7 of A097592.

%K nonn

%O 14,1

%A _Alois P. Heinz_, Jul 25 2018

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Last modified May 23 09:39 EDT 2022. Contains 353975 sequences. (Running on oeis4.)