Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #19 Sep 08 2022 08:45:28
%S 1,2,5,7,37,47,65,67,73,80,115,128,163,170,175,203,215,220,235,292,
%T 317,343,350,352,392,430,460,493,527,535,578,605,662,670,677,683,697,
%U 710,728,730,782,850,892,908,938,1003,1040,1048,1087,1235,1267,1285,1300
%N Numbers n such that (2*n)^2 + 1 and (2*n)^2 + 3 are both prime.
%H Harvey P. Dale, <a href="/A123232/b123232.txt">Table of n, a(n) for n = 1..1000</a>
%e a(4) = 7 because 14^2 + 1 = 197 and 14^2 + 3 = 199 which are both prime.
%p for i from 1 to 1000 do if(isprime(i^2 +1) and isprime(i^2+3)) then print(i/2); end if; end do;
%t Select[Range[1300],AllTrue[(2#)^2+{1,3},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Jan 15 2016 *)
%o (Magma) [n: n in [0..6000] | IsPrime((2*n)^2+1)and IsPrime((2*n)^2+3)] // _Vincenzo Librandi_, Nov 13 2010
%Y Cf. A001359.
%K nonn
%O 1,2
%A _Ben Paul Thurston_, Oct 06 2006