A187766 Even numbers k such that prime(k) -+ k are both composite.
12, 20, 36, 38, 40, 46, 52, 56, 58, 60, 62, 64, 74, 78, 80, 86, 88, 112, 118, 120, 122, 124, 128, 132, 134, 136, 138, 140, 142, 146, 156, 160, 162, 164, 166, 170, 176, 182, 184, 186, 188, 190, 194, 198, 208, 210, 212, 216
Offset: 1
Keywords
Programs
-
Mathematica
Select[2*Range[200],!PrimeQ[Prime[#]+#]&&!PrimeQ[Prime[#]-#]&] (* Harvey P. Dale, Dec 24 2013 *)
-
PARI
{forstep(i=2,220,2,p=prime(i);if(!isprime(p-i)&&!isprime(p+i),print1(i", ")))}
Comments