A193266 Numbers k such that k + 3 and k^2 + 9 are both prime.
2, 8, 10, 20, 38, 40, 58, 70, 98, 100, 110, 160, 170, 188, 190, 220, 308, 350, 380, 538, 568, 598, 628, 640, 680, 688, 698, 740, 748, 818, 850, 968, 1010, 1028, 1048, 1088, 1190, 1228, 1300, 1378, 1420, 1430, 1448, 1528, 1540, 1550, 1568, 1580, 1730, 1738
Offset: 1
Keywords
Examples
2 is in the sequence since 2 + 3 = 5 and 2^2 + 9 = 13 are both prime; 8 is in the sequence since 8 + 3 = 11 and 8^2 + 9 = 73 are both prime.
Programs
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Mathematica
Select[Prime[Range[3,300]]-3,PrimeQ[#^2+9]&] (* Harvey P. Dale, Nov 11 2014 *)
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PARI
{a=3;forstep(n=2,2000,2,if(isprime(n+a)&&isprime(n^2+a^2),print1(n",")))}