cp's OEIS Frontend

First differs from its subsequence A381315 at n = 40: a(40) = 432 = 2^4 * 3^3 is not a term of A381315.

Numbers k such that A295883(k) = 1.

The asymptotic density of this sequence is Product_{p prime} (1 - 1/p^3 + 1/p^4) * Sum_{p prime} (p-1)/(p^4 - p + 1) = 0.092831691827595439609... (Elma and Martin, 2024).

First differs from A374590 and A375432 at n = 25: A374590(25) = A375432(25) = 216 is not a term of this sequence.

Numbers k such that A382291(k) = 2, i.e., numbers whose number of infinitary divisors is twice the number of their unitary divisors.

Numbers whose prime factorization has a single exponent that is a sum of two distinct powers of 2 (A018900) and all the other exponents, if they exist, are powers of 2. Equivalently, numbers of the form p^e * m, where p is a prime, e is a term in A018900, and m is a term in A138302 that is coprime to p.

If k is a term then k^2 is also a term. If m is a term in A138302 that is coprime to k then k * m is also a term. The primitive terms, i.e., the terms that cannot be generated from smaller terms using these rules, are the numbers of the form p^(2^i+1), where p is prime and i >= 1.

Analogous to A060687, which is the sequence of numbers k with prime excess A046660(k) = 2.

The asymptotic density of this sequence is A271727 * Sum_{p prime} (((1 - 1/p)/f(1/p)) * Sum_{k>=1} 1/p^A018900(k)) = 0.11919967112489084407..., where f(x) = 1 - x^3 + Sum_{k>=2} (x^(2^k)-x^(2^k+1)).