OFFSET
2,1
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.
The median of a multiset is either the middle part (for odd length), or the average of the two middle parts (for even length).
EXAMPLE
The prime indices of 360 are {1,1,1,2,2,3}, with median 3/2, so a(360) = 3.
MATHEMATICA
prix[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Table[2*Median[prix[n]], {n, 2, 100}]
CROSSREFS
A316413 lists numbers whose prime indices have integer mean.
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 23 2023
STATUS
approved