OFFSET
1,5
EXAMPLE
We have 91 = prime(4) * prime(6), so a(91) = pi(4) * pi(6) = 6.
MATHEMATICA
primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Table[Times@@PrimePi/@primeMS[n], {n, 100}]
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
Gus Wiseman, Oct 25 2022
STATUS
approved