OFFSET
0,4
COMMENTS
Self-convolution inverse is A117211.
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..10000 (terms 0..1000 from Paul D. Hanna)
N. J. A. Sloane, Transforms
FORMULA
G.f.: A(x) = exp( Sum_{n>=1} A117212(n)*x^n/n ).
G.f.: A(x) = product_{k>=1}(1 + x^k)^mu(k) where mu(k) is the Möbius function, A008683 - Stuart Clary, Apr 15 2006
Weigh transform of A008683(n). - Vladeta Jovovic, Apr 20 2006
MATHEMATICA
nmax = 81; CoefficientList[ Series[ Product[ (1 + x^k)^(MoebiusMu[k]), {k, 1, nmax} ], {x, 0, nmax} ], x ] (* Stuart Clary, Apr 15 2006 *)
PROG
(PARI) {a(n)=if(n==0, 1, if(n==1, 1, -polcoeff(prod(i=1, n, sum(k=0, min(n\i, n-1), a(k)*x^(i*k))+x*O(x^n)), n, x)))}
CROSSREFS
KEYWORD
sign,look
AUTHOR
Paul D. Hanna, Mar 03 2006
STATUS
approved