A057950 Numbers primitive with respect to having more than one factorization into S-primes. See related sequences for definition.

441, 693, 1089, 1197, 1449, 1617, 1881, 1953, 2277, 2541, 2709, 2793, 2961, 3069, 3249, 3381, 3717, 3933, 4221, 4257, 4389, 4473, 4557, 4653, 4761, 4977, 5229, 5301, 5313, 5841, 5929, 6321, 6417, 6489, 6633, 6741, 6897, 6909, 7029, 7161, 7353, 7581

Offset

1,1

Comments

A subset of A057949, removing terms that are a multiple of a smaller term.

Cubefree numbers with exactly 4 prime factors, all congruent to 3 mod 4. - Charlie Neder, Nov 26 2018

Links

Eric M. Schmidt, Table of n, a(n) for n = 1..10000

Example

441 is in S = {1, 5, 9, ... 4i+1, ...}, 441 = 9*49 = 21^2, 9, 21 and 49 as S-primes (A057948). 441 is primitive because it is not divisible by any smaller numbers with more than 1 factorization into S-primes. Multiples of 441 within S are not primitive.

Crossrefs

Cf. A054520, A057948, A057949.

Cf. A004709 (cubefree numbers).

Sequence in context: A252201 A252194 A057949 * A343827 A250808 A202400

Adjacent sequences: A057947 A057948 A057949 * A057951 A057952 A057953

Keyword

nonn

Author

Jud McCranie, Oct 14 2000

Extensions

Definition edited and offset corrected by Eric M. Schmidt, Dec 11 2016

Status

approved