OFFSET
1,2
COMMENTS
a(n) is the product of indices of distinct prime factors of n if 1 is considered as a prime (see A008578).
LINKS
EXAMPLE
a(36) = 6 because 36 = 2^2 * 3^2 = prime(1)^2 * prime(2)^2 and (1 + 1) * (2 + 1) = 6.
MATHEMATICA
a[n_] := Times @@ ((PrimePi[#[[1]]] + 1) & /@ FactorInteger[n]); Table[a[n], {n, 1, 75}]
PROG
(PARI) a(n)={my(f=factor(n)[, 1]); prod(i=1, #f, 1 + primepi(f[i]))} \\ Andrew Howroyd, Oct 29 2019
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
Ilya Gutkovskiy, Oct 29 2019
STATUS
approved