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A057950 Numbers primitive with respect to having more than one factorization into S-primes. See related sequences for definition. 4
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 (list; graph; refs; listen; history; text; internal format)
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 * A250808 A202400 A014793

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

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Last modified March 18 19:58 EDT 2019. Contains 321293 sequences. (Running on oeis4.)