A240618 Primes p such that p*q*r + 2 is prime, where q and r are the next two primes after p.

3, 13, 257, 307, 409, 431, 587, 719, 733, 1031, 1109, 1123, 1129, 1237, 1657, 1987, 1999, 2143, 2179, 2239, 2411, 2467, 2843, 3041, 3191, 3433, 3691, 3943, 4051, 4219, 4289, 4561, 4567, 4721, 4817, 4831, 4943, 4993, 5521, 5563, 5623, 5689, 5813, 6257, 6983, 7043

Offset: 1

Author

K. D. Bajpai, Apr 09 2014

Keywords

• nonn

Comments

All the terms in the sequence, except a(1), are congruent to 1 mod 6.

Links

• K. D. Bajpai, Table of n, a(n) for n = 1..6606

Crossrefs

Cf. A000040, A048880, A051507, A240596.

Programs

Maple

KD := proc(n) local a,b; a:=ithprime(n)*ithprime(n+1)*ithprime(n+2); b:=a+2; if  isprime(b) then RETURN (ithprime(n)); fi; end: seq(KD(n), n=1..2000);

Mathematica

KD={}; Do[p=Prime[n]; If[PrimeQ[p*Prime[n+1]*Prime[n+2] + 2], AppendTo[KD,p]], {n,1000}]; KD