A139461 Numbers k such that 2*prime(k+2) + product (first k odd primes) is prime, i.e., k such that primorial(k+1)/2 + 2*prime(k+2) is prime.

1, 2, 3, 4, 8, 9, 11, 12, 27, 28, 37, 47, 64, 321, 415, 1222, 1649, 2937, 3600, 6149, 12481

Offset

1,2

Comments

a(22) > 25000. - Robert Price, Aug 06 2017

Links

Table of n, a(n) for n=1..21.

Mathematica

k = 1; a = {}; Do[k = k*Prime[n]; If[PrimeQ[k + 2*Prime[n + 1]], AppendTo[a, n - 1]], {n, 2, 2000}]; a (* Artur Jasinski *)

Crossrefs

Cf. A067026, A067027, A139439, A139440, A139441, A139442, A139443, A139444, A139445, A139446, A139447, A139448, A139449, A139450, A139451, A139452, A139453, A139454, A139455, A139456, A139457, A103514, A139460, A139462, A139463.

Sequence in context: A002971 A157318 A158031 * A126421 A116111 A253278

Adjacent sequences: A139458 A139459 A139460 * A139462 A139463 A139464

Keyword

nonn

Author

Artur Jasinski, Apr 22 2008

Extensions

a(16)-a(21) from Robert Price, Aug 06 2017

Status

approved