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A264463 Number of permutations of [n] with exactly four (possibly overlapping) occurrences of the generalized pattern 23-1. 2
3, 62, 624, 5513, 46880, 396545, 3388893, 29497132, 262619041, 2397130075, 22458202716, 216063700398, 2134707078315, 21655074753266, 225471830153938, 2408463527492433, 26380434283682048, 296130434080550183, 3404883834560222589, 40077202708717399396 (list; graph; refs; listen; history; text; internal format)
OFFSET
5,1
LINKS
EXAMPLE
a(5) = 3: 34512, 34521, 45231.
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, 5), polynom), j=1..o))
end:
a:= n-> coeff(b(n, 0), x, 4):
seq(a(n), n=5..25);
CROSSREFS
Column k=4 of A260670.
Sequence in context: A220775 A089157 A068886 * A239576 A279974 A275746
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Nov 14 2015
STATUS
approved

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Last modified May 24 21:45 EDT 2024. Contains 372782 sequences. (Running on oeis4.)