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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
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
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Nov 14 2015
STATUS
approved

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Last modified February 24 22:04 EST 2024. Contains 370307 sequences. (Running on oeis4.)