A139461 - OEIS

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

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OFFSET

1,2

COMMENTS

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

LINKS

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

KEYWORD

nonn

AUTHOR

EXTENSIONS

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

STATUS

approved