|
|
A366676
|
|
G.f. satisfies A(x) = 1 + x^3 + x*A(x)^3.
|
|
11
|
|
|
1, 1, 3, 13, 58, 288, 1512, 8250, 46296, 265491, 1548976, 9165156, 54865737, 331694167, 2022232068, 12419023617, 76755164643, 477049187268, 2979758649996, 18695276174079, 117766227611046, 744527923478730, 4722464911515423, 30044091589750350
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
LINKS
|
|
|
FORMULA
|
a(n) = Sum_{k=0..floor(n/3)} binomial(2*(n-3*k)+1,k) * binomial(3*(n-3*k),n-3*k)/(2*(n-3*k)+1).
|
|
PROG
|
(PARI) a(n) = sum(k=0, n\3, binomial(2*(n-3*k)+1, k)*binomial(3*(n-3*k), n-3*k)/(2*(n-3*k)+1));
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|