

A321110


Number of permutations p of [n] such that in 0p the largest upjump equals three and no downjump 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
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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(uj, o+j1, k), j=1..min(2, u))+
add(b(u+j1, oj, k), j=1..min(k, o)))
end:
a:= n> (k> b(0, n, k)b(0, n, k1))(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



