OFFSET
1,2
COMMENTS
Zeros are ignored when computing GCD, and the empty set has GCD 0.
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.
EXAMPLE
85 has prime indices {3,7}, so a(85) = GCD(4,8) = 4.
MATHEMATICA
Table[GCD@@(PrimePi/@First/@If[n==1, {}, FactorInteger[n]]+1), {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Oct 09 2019
STATUS
approved