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

Author

Zak Seidov, Jan 04 2013

Keywords

• nonn

Comments

Even numbers not in A064269 and not in A064402.

Interestingly, prime(12) = 37 and both 37 - 12 = 25 and 37 + 12 = 49 are squares. Is there another such n?

Crossrefs

Cf. A064269, A064402.

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", ")))}