OFFSET
1,1
COMMENTS
Subsequence of A046101 and first differs from it at n = 98: A046101(98) = 1296 = 2^4 * 3^4 is not a term of this sequence.
Numbers k such that the powerful part of k, A057521(k), is a prime power whose exponent is larger than 3 (A246550).
The asymptotic density of this sequence is (1/zeta(4)) * Sum_{p prime} 1/(p^4-1) = 0.075131780079404733755... .
LINKS
EXAMPLE
16 = 2^4 is a term since its prime factorization has exactly one exponent, 4, that is larger than 3.
MATHEMATICA
q[n_] := Count[FactorInteger[n][[;; , 2]], _?(# > 3 &)] == 1; Select[Range[1000], q]
PROG
(PARI) is(k) = #select(x -> x > 3, factor(k)[, 2]) == 1;
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Amiram Eldar, Aug 01 2024
STATUS
approved