OFFSET
1,3
FORMULA
Also a(n) = Sum_{k=1..n} 2^omega(k)*mu(k). - Benoit Cloitre, Jun 13 2007
MATHEMATICA
Accumulate[Table[DivisorSigma[0, n]MoebiusMu[n], {n, 100}]] (* Harvey P. Dale, Aug 15 2016 *)
PROG
(PARI) v=[]; for(n=1, 250, v=concat(v, sum(k=1, n, numdiv(k)*moebius(k)))); v
CROSSREFS
KEYWORD
sign
AUTHOR
Jason Earls, Jul 03 2001
STATUS
approved