OFFSET
1,2
COMMENTS
First differs from A115975 at a(42). - Omar E. Pol, Apr 26 2020
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..218 from Kevin Foote)
MATHEMATICA
Select[Range[250], Length[(f = FactorInteger[#])] == 1 && ((e = f[[1, 2]]) == 1 || PrimeQ[e]) &] (* Amiram Eldar, Apr 27 2020 *)
PROG
(PARI) isok(n) = if (n==1, return (1)); my(k=isprimepower(n)); (k==1) || isprime(k); \\ Michel Marcus, Apr 27 2020
(Python)
from sympy import primepi, integer_nthroot, primerange
def A334393(n):
def f(x): return int(n-1+x-primepi(x)-sum(primepi(integer_nthroot(x, p)[0]) for p in primerange(x.bit_length())))
m, k = n, f(n)
while m != k:
m, k = k, f(k)
return m # Chai Wah Wu, Aug 13 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Kevin Foote, Apr 26 2020
STATUS
approved