|
|
A241693
|
|
Number of Carlitz compositions of n with exactly three descents.
|
|
2
|
|
|
3, 11, 31, 78, 175, 363, 715, 1342, 2421, 4237, 7208, 11971, 19473, 31083, 48787, 75437, 115046, 173263, 257972, 380039, 554400, 801452, 1148805, 1633699, 2306108, 3232635, 4501745, 6230400, 8572442, 11729536, 15965001, 21621202, 29141879, 39100192, 52233835
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
9,1
|
|
COMMENTS
|
No two adjacent parts of a Carlitz composition are equal.
|
|
LINKS
|
|
|
MAPLE
|
b:= proc(n, i) option remember; `if`(n=0, 1,
convert(series(add(`if`(i=j, 0, b(n-j, j)*
`if`(j<i, x, 1)), j=1..n), x, 4), polynom))
end:
a:= n-> coeff(b(n, 0), x, 3):
seq(a(n), n=9..50);
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|