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A059452
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Safe primes (A005385) which are not Sophie Germain primes.
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23
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7, 47, 59, 107, 167, 227, 263, 347, 383, 467, 479, 503, 563, 587, 839, 863, 887, 983, 1187, 1283, 1307, 1319, 1367, 1487, 1523, 1619, 1823, 1907, 2027, 2099, 2207, 2447, 2579, 2879, 2999, 3119, 3167, 3203, 3467, 3947, 4007, 4079, 4127, 4139, 4259, 4283
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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347 is here because 173 is a prime but 695 is not. Except for 7, these primes are congruent to 11 modulo 12. Terminal primes in complete Cunningham chains of first kind, i.e., the chains cannot be continued from these primes.
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MATHEMATICA
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PROG
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(Python)
from itertools import count, islice
from sympy import isprime, prime
def A059452_gen(): # generator of terms
return filter(lambda p:isprime(p>>1) and not isprime(p<<1|1), (prime(i) for i in count(1)))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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