OFFSET
5,1
LINKS
Alois P. Heinz, Table of n, a(n) for n = 5..200
FORMULA
a(n) = A197365(n,2).
EXAMPLE
a(5) = 3: 13254, 14253, 15243.
a(6) = 56: 124365, 125364, 126354, ..., 613254, 614253, 615243.
a(7) = 753: 1235476, 1236475, 1237465, ..., 7613254, 7614253, 7615243.
a(8) = 9024: 12346587, 12347586, 12348576, ..., 87613254, 87614253, 87615243.
MAPLE
b:= proc(u, o, t) option remember; series(`if`(u+o=0, 1,
add(b(u-j, o+j-1, 0)*`if`(j<=t, x, 1), j=1..u)+
add(b(u+j-1, o-j, j-1), j=1..o)), x, 3)
end:
a:= n-> coeff(b(n, 0$2), x, 2):
seq(a(n), n=5..30);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Oct 28 2015
STATUS
approved