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A264463 Number of permutations of [n] with exactly four (possibly overlapping) occurrences of the generalized pattern 23-1. 2

%I #5 Nov 14 2015 16:45:05

%S 3,62,624,5513,46880,396545,3388893,29497132,262619041,2397130075,

%T 22458202716,216063700398,2134707078315,21655074753266,

%U 225471830153938,2408463527492433,26380434283682048,296130434080550183,3404883834560222589,40077202708717399396

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

%H Alois P. Heinz, <a href="/A264463/b264463.txt">Table of n, a(n) for n = 5..500</a>

%e a(5) = 3: 34512, 34521, 45231.

%p b:= proc(u, o) option remember; `if`(u+o=0, 1, add(

%p b(u-j, o+j-1), j=1..u) +add(convert(series(

%p b(u+j-1, o-j)*x^u, x, 5), polynom), j=1..o))

%p end:

%p a:= n-> coeff(b(n, 0), x, 4):

%p seq(a(n), n=5..25);

%Y Column k=4 of A260670.

%K nonn

%O 5,1

%A _Alois P. Heinz_, Nov 14 2015

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Last modified June 25 13:13 EDT 2024. Contains 373705 sequences. (Running on oeis4.)