A063442 Primes of the form p*q+4 where p and q are consecutive primes.

19, 1151, 4091, 30971, 47057, 55691, 141371, 148991, 223697, 256031, 265193, 329471, 355211, 948671, 1223231, 1545017, 1607747, 1653791, 2062091, 2238011, 2390111, 2572811, 3041531, 3625211, 4305593, 4553951, 5541311, 5635871

Offset

1,1

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Example

prime(449) * prime(450) + 4 = 3169 * 3181 + 4 = 10080593, a prime.

Mathematica

f[n_]:=Prime[n]*Prime[n+1]+4; lst={}; Do[If[PrimeQ[f[n]], AppendTo[lst, f[n]]], {n, 6!}]; lst (* Vladimir Joseph Stephan Orlovsky, Feb 10 2010 *)
Select[Times@@#+4&/@Partition[Prime[Range[500]], 2, 1], PrimeQ] (* Harvey P. Dale, Sep 21 2020 *)

Prog

(PARI) j=[]; for(n=1, 500, x=(prime(n)*prime(n+1))+4; if(isprime(x), j=concat(j, x))); j
(PARI) { n=0; for (m=1, 10^9, if (isprime(a=prime(m)*prime(m + 1) + 4), write("b063442.txt", n++, " ", a); if (n==1000, break)) ) } \\ Harry J. Smith, Aug 21 2009

Crossrefs

Sequence in context: A098635 A217828 A217829 * A091750 A316332 A319025

Adjacent sequences: A063439 A063440 A063441 * A063443 A063444 A063445

Keyword

easy,nonn

Author

Jason Earls, Jul 23 2001

Status

approved