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A321111 Number of permutations p of [n] such that in 0p the largest up-jump equals four and no down-jump is larger than 2. 2
4, 20, 108, 586, 3098, 16230, 85150, 446972, 2349616, 12376800, 65353448, 345933358, 1835637246, 9764363438, 52064375292, 278256581910, 1490475179006, 8000983513636, 43039329754332, 231982689315468, 1252791611642654, 6777998215153164, 36735901427197962 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 4..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))(4):

seq(a(n), n=4..30);

CROSSREFS

Column k=4 of A291680.

Sequence in context: A243585 A263965 A265084 * A319321 A321574 A225621

Adjacent sequences:  A321108 A321109 A321110 * A321112 A321113 A321114

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Oct 27 2018

STATUS

approved

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Last modified June 28 11:24 EDT 2022. Contains 354905 sequences. (Running on oeis4.)