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A264468 Number of permutations of [n] with exactly nine (possibly overlapping) occurrences of the generalized pattern 23-1. 2
18, 780, 15627, 235045, 3086010, 37816568, 449766437, 5291113080, 62237008779, 736806459069, 8816027319934, 106900514193980, 1315953951437664, 16464756848575162, 209528329365176670, 2713295547732215190, 35762229764646245816, 479809424452611001696 (list; graph; refs; listen; history; text; internal format)
OFFSET

7,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 7..500

EXAMPLE

a(7) = 18: 3567241, 4567123, 4567132, 4567213, 4567312, 4567321, 4672351, 4673512, 4673521, 5671342, 5672314, 5672413, 5672431, 5673241, 5674231, 6734512, 6734521, 6745231.

MAPLE

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

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

      b(u+j-1, o-j)*x^u, x, 10), polynom), j=1..o))

    end:

a:= n-> coeff(b(n, 0), x, 9):

seq(a(n), n=7..25);

CROSSREFS

Column k=9 of A260670.

Sequence in context: A159873 A259458 A180781 * A303991 A033471 A128074

Adjacent sequences:  A264465 A264466 A264467 * A264469 A264470 A264471

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Nov 14 2015

STATUS

approved

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Last modified August 12 16:32 EDT 2022. Contains 356077 sequences. (Running on oeis4.)