OFFSET
1,7
MATHEMATICA
PrimeFactors[n_Integer] := Flatten[ Table[ # [[1]], {1}] & /@ FactorInteger[n]]; a[1] = 1; a[n_] := a[n] = (Plus @@ (a[ # ] & /@ Complement[ Range[ PrimePi[n]], PrimePi[ PrimeFactors[n]]])); Table[ a[n], {n, 80}] (* Robert G. Wilson v, May 04 2004 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Leroy Quet, Apr 26 2004
EXTENSIONS
More terms from Robert G. Wilson v, May 04 2004
STATUS
approved