|
|
A249636
|
|
G.f.: Sum_{n>=0} x^n / Product_{k=n..2*n-1} (1 - k*x).
|
|
1
|
|
|
1, 1, 2, 7, 33, 186, 1213, 8949, 73300, 657589, 6396829, 66936872, 748528619, 8896663389, 111873459298, 1482522176651, 20633389026901, 300705290677218, 4576892504775417, 72584518271451169, 1196883163316172252, 20482129284796798609, 363138667441109774065, 6659922487212111452776
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
LINKS
|
|
|
EXAMPLE
|
G.f.: A(x) = 1 + x + 2*x^2 + 7*x^3 + 33*x^4 + 186*x^5 + 1213*x^6 +...
where
A(x) = 1 + x/(1-x) + x^2/((1-2*x)*(1-3*x)) + x^3/((1-3*x)*(1-4*x)*(1-5*x)) + x^4/((1-4*x)*(1-5*x)*(1-6*x)*(1-7*x)) + x^5/((1-5*x)*(1-6*x)*(1-7*x)*(1-8*x)*(1-9*x)) +...
|
|
PROG
|
(PARI) {a(n)=polcoeff(sum(m=0, n, x^m/prod(k=m, 2*m-1, 1-k*x +x*O(x^n))), n)}
for(n=0, 30, print1(a(n), ", "))
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|