OFFSET
1,4
COMMENTS
A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.
LINKS
Winston de Greef, Table of n, a(n) for n = 1..10000
EXAMPLE
The 0-prepended prime indices of 100 are {0,1,1,3,3}, with differences (1,0,2,0), with mean 3/4, so a(100) = 4.
MATHEMATICA
prix[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Table[If[n==1, 0, Denominator[Mean[Differences[Prepend[prix[n], 0]]]]], {n, 100}]
PROG
(PARI) a(n) = if (n==1, 0, my(f=factor(n)); denominator(primepi(vecmax(f[, 1]))/ bigomega(f))); \\ Michel Marcus, Feb 20 2023
KEYWORD
nonn,frac
AUTHOR
Gus Wiseman, Feb 19 2023
STATUS
approved