OFFSET
1,2
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..20000
FORMULA
Multiplicative with a(p^e) = e+1 if p = 2; ((p-1)^(e+1)-1)/(p-2) if p > 2. - David W. Wilson, Sep 01 2001
Dirichlet g.f.: zeta(s) * Product_{p prime} 1 / (1 - p^(1-s) + p^(-s)). - Ilya Gutkovskiy, Feb 11 2022
Sum_{k=1..n} a(k) ~ Pi^6 * n^2 / (1890 * zeta(3)). - Vaclav Kotesovec, Feb 11 2022
PROG
(PARI)
A003958(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1]--); factorback(f); };
(PARI) for(n=1, 100, print1(direuler(p=2, n, 1/(1 - X)/(1 - p*X + X))[n], ", ")) \\ Vaclav Kotesovec, Feb 11 2022
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
EXTENSIONS
More terms from David W. Wilson, Aug 29 2001
STATUS
approved