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A060254
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Primes which are the sum of two consecutive composite numbers.
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21
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17, 19, 29, 31, 41, 43, 53, 67, 71, 79, 89, 97, 101, 103, 109, 113, 127, 131, 137, 139, 149, 151, 163, 173, 181, 191, 197, 199, 211, 223, 229, 233, 239, 241, 251, 257, 269, 271, 281, 283, 293, 307, 311, 317, 331, 337, 349, 353, 367, 373, 379, 389, 401, 409
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| For the smaller of the consecutive composite pair (p-+1)/2, see A096784
This sequence also contains exactly those odd primes p where neither p-1 nor p+1 is the product of exactly 2 (not necessarily distinct) primes. [From Leroy Quet Sep 09 2008]
5 together with the prime numbers A060254=(5,17,19,29,31,41,43,53,..)=primes which are the sum of two consecutive nonprime numbers. [From Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Aug 30 2009]
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EXAMPLE
| The prime 19 is an entry since it is the sum of 9=3^2 and 10=2*5.
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MATHEMATICA
| 2Select[ Range[210], PrimeQ[ # ] == PrimeQ[ # + 1] == False && PrimeQ[2# + 1] == True &] + 1
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CROSSREFS
| Cf. A096783, A096784, A096785, A096786, A096787, A096788, A096677.
Sequence in context: A175384 A053689 A176462 * A190792 A137796 A125213
Adjacent sequences: A060251 A060252 A060253 * A060255 A060256 A060257
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KEYWORD
| nonn
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 22 2001
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