A124684 Primes of the form (p*q - 2)/5 where p and q are successive primes.

229, 1153, 14149, 15013, 189733, 214657, 253573, 350593, 514561, 522289, 725041, 853669, 1304581, 1453681, 2027569, 2183281, 2212453, 2469637, 3238513, 4166017, 4331941, 4467013, 5234689, 5510371, 5992933, 6102913, 8100097, 8130673

Offset: 1

Author

Cino Hilliard, Dec 27 2006

Keywords

• easy
• nonn

Comments

These numbers times 5 are semiprimes.

Examples

			31*37 = 1147, 1147-2 = 1145, 1145/5 = 229 is a term.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A123921.

Programs

Mathematica

Select[(Times @@@ Partition[Prime[Range[1000]], 2, 1] - 2) / 5, PrimeQ] (* Amiram Eldar, May 26 2024 *)

PARI

g(n,p=5) = { for(x=1,n, y=prime(x)*prime(x+1)-2; if(y%p==0,if(isprime(y/p), print1(y/p, ", ")))) }