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A115719
Products of two primes that are not Chen primes.
0
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).
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
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Mar 09 2006
STATUS
approved