|
|
A192497
|
|
G.f. satisfies: A(x) = 1 + Sum_{n>=1} x^n*A(x)^sigma(n), where sigma(n) = A000203(n) is the sum of divisors of n.
|
|
0
|
|
|
1, 1, 2, 6, 20, 73, 281, 1124, 4633, 19547, 84023, 366695, 1620513, 7237034, 32609389, 148066067, 676805101, 3111807931, 14381741533, 66775448718, 311332294182, 1456999560630, 6841841485578, 32228152992893, 152241706312812, 721055062770213
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
LINKS
|
|
|
EXAMPLE
|
G.f.: A(x) = 1 + x + 2*x^2 + 6*x^3 + 20*x^4 + 73*x^5 + 281*x^6 +...
The g.f. satisfies:
A(x) = 1 + x*A(x) + x^2*A(x)^3 + x^3*A(x)^4 + x^4*A(x)^7 + x^5*A(x)^6 + x^6*A(x)^12 + x^7*A(x)^8 + x^8*A(x)^15 +...
|
|
PROG
|
(PARI) {a(n)=local(A=1+x); for(i=1, n, A=1+sum(m=1, n, x^m*(A+x*O(x^n))^sigma(m))); polcoeff(A, n)}
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|