A093706 Primes p such that (pp'-1)/2 is prime, where p' denotes the next prime after p.

3, 5, 11, 29, 41, 71, 137, 281, 461, 599, 641, 787, 827, 881, 1091, 1129, 1301, 1409, 1607, 1627, 1951, 2129, 2267, 2357, 2381, 2557, 2687, 2887, 2917, 3469, 3527, 3557, 3581, 3967, 4127, 4229, 4337, 4547, 4889, 5009, 5309, 5741, 6131, 6133, 6247, 6343

Offset

1,1

Links

Hugo Pfoertner, Table of n, a(n) for n = 1..10000

Mathematica

Prime[ Select[ Range[850], PrimeQ[(Prime[ # ]Prime[ # + 1] - 1)/2] &]]
Transpose[Select[Partition[Prime[Range[900]], 2, 1], PrimeQ[ (Times@@#- 1)/2]&]][[1]] (* Harvey P. Dale, Sep 17 2011 *)

Prog

(PARI) isA093706(n) = if(n<3, 0, isprime(n) && isprime((n*nextprime(n+1)-1)/2)) \\ Michael B. Porter, Dec 15 2009

Crossrefs

Cf. A048797.

Sequence in context: A368808 A275920 A191025 * A109945 A045536 A319393

Adjacent sequences: A093703 A093704 A093705 * A093707 A093708 A093709

Keyword

nonn

Author

Robert G. Wilson v, Apr 10 2004

Status

approved