|
|
A305968
|
|
Number of length-n restricted growth strings (RGS) with growth <= eight and fixed first element.
|
|
3
|
|
|
1, 1, 9, 117, 1905, 36585, 802221, 19664325, 530764089, 15596609985, 494555435781, 16802009359677, 608027982857169, 23322183958778553, 944242763282027421, 40207158379868421429, 1795007963258388557673, 83786699444454149125041, 4079132811705470375924277
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
LINKS
|
|
|
FORMULA
|
a(n) = (n-1)! * [x^(n-1)] exp(x+Sum_{j=1..8} (exp(j*x)-1)/j) for n>0, a(0) = 1.
|
|
MAPLE
|
b:= proc(n, m) option remember; `if`(n=0, 1,
add(b(n-1, max(m, j)), j=1..m+8))
end:
a:= n-> b(n, -7):
seq(a(n), n=0..25);
# second Maple program:
a:= n-> `if`(n=0, 1, (n-1)!*coeff(series(exp(x+add(
(exp(j*x)-1)/j, j=1..8)), x, n), x, n-1)):
seq(a(n), n=0..25);
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|