A115719 Products of two primes that are not Chen primes.

1849, 2623, 3139, 3397, 3721, 4171, 4429, 4453, 4819, 5329, 5767, 5917, 6241, 6283, 6493, 7009, 7081, 7439, 7519, 7663, 8137, 8299, 9211, 9409, 9589, 9847, 9943, 9991, 10363, 10553, 10609, 11023, 11653, 11773, 11899, 11911, 11929, 12169, 12629, 12877

Offset

1,1

Comments

Subset of semiprimes A001358 such that neither prime factor is a Chen prime. See also A109611 (Chen primes: primes p such that p + 2 is either a prime or a semiprime), A102540 (primes that are not Chen primes).

Links

Table of n, a(n) for n=1..40.

Formula

{p*q such that p is in A102540 and q is in A102540}. {s such that s is in A001358 AND p|s IMPLIES NOT(p is in A109611}.

Example

a(1) = 1849 = A102540(1)*A102540(1) = 43*43.
a(2) = 2623 = A102540(1)*A102540(2) = 43*61.
a(36) = 14701 = A102540(2)*A102540(13) = 61 * 241.

Crossrefs

Cf. A000040, A001358, A109611, A102540.

Sequence in context: A236030 A237892 A326318 * A062670 A206468 A031764

Adjacent sequences: A115716 A115717 A115718 * A115720 A115721 A115722

Keyword

easy,nonn

Author

Jonathan Vos Post, Mar 09 2006

Status

approved