OFFSET
1,1
COMMENTS
A prime index of n is a number m such that prime(m) divides n.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
FORMULA
a(n) ~ kn log n, where k = Pi^2/6. - Charles R Greathouse IV, Aug 03 2023
MAPLE
map(ithprime, select(numtheory:-issqrfree, [$1..500])); # Robert Israel, Nov 06 2023
MATHEMATICA
Prime/@Select[Range[100], SquareFreeQ]
PROG
(PARI) forprime(p=1, 500, if(issquarefree(primepi(p)), print1(p, ", "))) \\ Felix Fröhlich, Apr 10 2018
(PARI) list(lim)=my(v=List(), k); forprime(p=2, lim\1, if(issquarefree(k++), listput(v, p))); Vec(v) \\ Charles R Greathouse IV, Aug 03 2023
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Gus Wiseman, Apr 08 2018
STATUS
approved