OFFSET
1,1
COMMENTS
Primes in A247175.
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
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
Juri-Stepan Gerasimov, Nov 30 2014
STATUS
approved