OFFSET
0,8
COMMENTS
Self-convolution inverse is A117209.
LINKS
Paul D. Hanna, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: A(x) = exp( -Sum_{n>=1} A023900(n)*x^n/n ), where A023900 is the Dirichlet inverse of Euler totient function.
Euler transform of the negative of the Möbius function. - Stuart Clary, Apr 15 2006
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
MATHEMATICA
nmax = 106; CoefficientList[ Series[ Product[ (1 - x^k)^(MoebiusMu[k]), {k, 1, nmax} ], {x, 0, nmax} ], x ] (* Stuart Clary, Apr 15 2006 *)
PROG
(PARI) {a(n)=polcoeff(exp(-sum(k=1, n+1, sumdiv(k, d, d*moebius(d))*x^k/k)+x*O(x^n)), n)}
CROSSREFS
KEYWORD
sign
AUTHOR
Paul D. Hanna, Mar 03 2006
STATUS
approved