A115395 Primes p such that p+-6 are semiprimes.

71, 127, 139, 149, 211, 241, 293, 397, 401, 409, 421, 479, 487, 491, 499, 521, 523, 617, 661, 673, 691, 701, 743, 761, 773, 787, 797, 809, 907, 911, 967, 1049, 1061, 1151, 1153, 1163, 1171, 1201, 1213, 1249, 1279, 1399, 1409, 1471, 1523, 1571, 1583, 1597

Offset: 1

Author

Zak Seidov, Mar 08 2006

Keywords

• nonn

Examples

			71-6=65=5*13 (semiprime), 71+6=77=7*11 (semiprime).
		

Links

• K. D. Bajpai, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A063643 Primes p such that p+-2 are semiprimes, A117328 Primes p such that p+-4 are semiprimes.

Programs

Mathematica

A115395 = {}; k = Prime[n]; Do[If[PrimeOmega[k + 6] == 2 && PrimeOmega[k - 6] == 2, AppendTo[A115395, k]], {n, 1000}]; A115395  (* K. D. Bajpai, Jun 24 2014 *)

PARI

lista(nn) = {pr = primes(nn); pp = select(i->((bigomega(i-6) == 2) && (bigomega(i+6) == 2)), pr); print(pp);} \\ Michel Marcus, Oct 09 2013