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A302491
Prime numbers of squarefree index.
14
2, 3, 5, 11, 13, 17, 29, 31, 41, 43, 47, 59, 67, 73, 79, 83, 101, 109, 113, 127, 137, 139, 149, 157, 163, 167, 179, 181, 191, 199, 211, 233, 241, 257, 269, 271, 277, 283, 293, 313, 317, 331, 347, 349, 353, 367, 373, 389, 397, 401, 421, 431, 439, 443, 449, 461
OFFSET
1,1
COMMENTS
A prime index of n is a number m such that prime(m) divides n.
LINKS
FORMULA
a(n) = A000040(A005117(n)).
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
KEYWORD
nonn,easy
AUTHOR
Gus Wiseman, Apr 08 2018
STATUS
approved