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A321110 Number of permutations p of [n] such that in 0p the largest up-jump equals three and no down-jump is larger than 2. 2
2, 8, 36, 156, 666, 2860, 12336, 53518, 233874, 1029134, 4559664, 20335346, 91254770, 411885192, 1869127696, 8524561158, 39058221662, 179724281242, 830256254372, 3849435933628, 17907743518356, 83566689375980, 391087227771308, 1835146738581226, 8632600618453808 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 3..1000

MAPLE

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

      add(b(u-j, o+j-1, k), j=1..min(2, u))+

      add(b(u+j-1, o-j, k), j=1..min(k, o)))

    end:

a:= n-> (k-> b(0, n, k)-b(0, n, k-1))(3):

seq(a(n), n=3..30);

CROSSREFS

Column k=3 of A291680.

Sequence in context: A295501 A283847 A123290 * A228791 A088675 A228197

Adjacent sequences:  A321107 A321108 A321109 * A321111 A321112 A321113

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Oct 27 2018

STATUS

approved

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Last modified August 18 14:22 EDT 2022. Contains 356215 sequences. (Running on oeis4.)