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A247197
Primes p such that 2*p^2 + 3 and 2*p^2 + 5 are also primes.
2
2, 7, 23, 47, 887, 1297, 1657, 2207, 2357, 2753, 4583, 4657, 6967, 8353, 8363, 10453, 12203, 12343, 13967, 16217, 16903, 21737, 23357, 23497, 25447, 29017, 32363, 36083, 40847, 41603, 41617, 43633, 45757, 46933, 48407, 52313, 60167, 60457, 66173, 67867, 71713, 72497, 72823, 73897
OFFSET
1,1
COMMENTS
Primes in A247175.
LINKS
EXAMPLE
2 is in this sequence because 2*2^2 + 3 = 11, 2*2^2 + 5 = 13 and 2 are all primes.
MATHEMATICA
a247197[n_Integer] := Select[Prime /@ Range[n], And[PrimeQ[2*#^2 + 3], PrimeQ[2*#^2 + 5]] &]; a247197[7500] (* Michael De Vlieger, Nov 30 2014 *)
Select[Prime[Range[7300]], AllTrue[2#^2+{3, 5}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jan 21 2019 *)
PROG
(Magma) [ n: n in [1..70000] | IsPrime(n) and IsPrime(2*(n^2+2)-1) and IsPrime(2*(n^2+2)+1) ];
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved