OFFSET
0,3
COMMENTS
Self-convolution equals A299436.
LINKS
Paul D. Hanna, Table of n, a(n) for n = 0..1000
EXAMPLE
G.f.: A(x) = 1 + x + 2*x^2 + 3*x^3 + 7*x^4 + 9*x^5 + 27*x^6 + 33*x^7 + 73*x^8 + 100*x^9 + 203*x^10 + 269*x^11 + 987*x^12 + 1163*x^13 + 2283*x^14 + ...
such that
log(A(x)) = x + 3*x^2/2 + 4*x^3/3 + 15*x^4/4 + 6*x^5/5 + 84*x^6/6 + 8*x^7/7 + 135*x^8/8 + 40*x^9/9 + 198*x^10/10 + 12*x^11/11 + 5460*x^12/12 + 14*x^13/13 + 360*x^14/14 + 384*x^15/15 + ... + A020696(n)/2*x^n/n + ...
PROG
(PARI) A020696(n) = {d = divisors(n); return (prod(i=1, #d, d[i]+1)); } \\ after Michel Marcus
{a(n) = my(A = exp( sum(m=1, n, A020696(m)/2*x^m/m ) +x*O(x^n) )); polcoeff(A, n)}
for(n=0, 40, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Feb 12 2018
STATUS
approved