

A292176


Number of permutations p of [n] such that 0p has a nonincreasing jump sequence beginning with ten.


2



10061, 37702, 107175, 285492, 786489, 2249024, 6929078, 22322520, 77416352, 274792342, 1035050705, 2962838350, 7926847142, 20648853479, 54254560137, 143941539439, 393399319076, 1083862520072, 3084318416024, 8650938117110, 24829005575685, 65609605382112
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

10,1


COMMENTS

An upjump j occurs at position i in p if p_{i} > p_{i1} and j is the index of p_i in the increasingly sorted list of those elements in {p_{i}, ..., p_{n}} that are larger than p_{i1}. A downjump j occurs at position i in p if p_{i} < p_{i1} and j is the index of p_i in the decreasingly sorted list of those elements in {p_{i}, ..., p_{n}} that are smaller than p_{i1}. First index in the lists is 1 here.


LINKS

Alois P. Heinz, Table of n, a(n) for n = 10..2000


MAPLE

b:= proc(u, o, t) option remember; `if`(u+o=0, 1,
add(b(uj, o+j1, j), j=1..min(t, u))+
add(b(u+j1, oj, j), j=1..min(t, o)))
end:
a:= n> b(0, n, 10)b(0, n, 9):
seq(a(n), n=10..50);


CROSSREFS

Column k=10 of A291684.
Sequence in context: A203089 A187113 A023356 * A198484 A252200 A234773
Adjacent sequences: A292173 A292174 A292175 * A292177 A292178 A292179


KEYWORD

nonn


AUTHOR

Alois P. Heinz, Sep 10 2017


STATUS

approved



