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A230225
Primes p such that 2*p+1 and 2*p+3 are not prime.
2
31, 37, 59, 61, 71, 79, 101, 103, 107, 109, 149, 151, 163, 181, 211, 241, 257, 263, 271, 311, 313, 317, 331, 347, 367, 373, 389, 401, 421, 433, 449, 457, 461, 479, 499, 521, 541, 569, 571, 577, 587, 601, 619, 631, 661, 673, 677, 691, 701, 709, 727, 733, 751
OFFSET
1,1
LINKS
EXAMPLE
31 is in the sequence because 2*31+1=63 and 2*31+3=65 are not prime.
MATHEMATICA
Select[Range[10^3], PrimeQ[#]&&!PrimeQ[2 # + 1]&&!PrimeQ[2 # + 3]&]
Select[Prime[Range[200]], NoneTrue[2#+{1, 3}, PrimeQ]&] (* Harvey P. Dale, Sep 19 2021 *)
PROG
(Magma) [p: p in PrimesUpTo(2500)|not IsPrime(2*p+1) and not IsPrime(2*p+3)];
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Oct 12 2013
STATUS
approved