A245665 Number of permutations of length n with longest increasing subsequence of length 9.

1, 81, 3961, 153341, 5213287, 164060352, 4927007100, 143938455225, 4142847526101, 118504614869214, 3389618010035458, 97376389179852540, 2818543211543628620, 82388635477750176388, 2436180769576352799396, 72958306889459609898731, 2214789502139053994814716

Offset: 9

Author

Alois P. Heinz, Jul 28 2014

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 9..60

Crossrefs

Column k=9 of A047874.

Programs

Maple

h:= proc(l) local n; n:= nops(l); add(i, i=l)! /mul(mul(1+l[i]-j
    +add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n) end:
g:= (n, i, l)-> `if`(n=0 or i=1, h([l[], 1$n])^2, `if`(i<1, 0,
                add(g(n-i*j, i-1, [l[], i$j]), j=0..n/i))):
a:= n-> g(n-9, min(n-9, 9), [9]):
seq(a(n), n=9..30);