A339475 Numbers at the start of a run of exactly 2 consecutive primes that are Sophie Germain primes.

23, 83, 173, 233, 653, 1013, 1223, 1499, 1889, 2063, 2393, 2543, 2693, 2963, 3803, 4373, 5039, 6101, 6263, 6323, 6491, 7079, 7643, 7883, 9473, 10691, 13883, 14153, 14303, 15161, 16811, 17669, 19553, 19913, 21701, 22259, 22343, 22409, 22469, 25913, 27551, 28001

Offset

1,1

Comments

Similar to A339474, but does not include numbers at the start of a run of 3 or more consecutive primes that are Sophie Germain primes.

Links

Jon E. Schoenfield, Table of n, a(n) for n = 1..10000

Example

23 is a term: 23 and 29 are consecutive primes, each is a Sophie Germain prime, and neither the prime before 23 (19)nor the one after 29 (31) is a Sophie Germain prime, so the length of the run is exactly 2.
2 is not a term: it is at the start of a run of 3 consecutive primes that are Sophie Germain primes, i.e., 2, 3, and 5.
Similarly, 20753 is not a term; it is at the start of a run of 3 consecutive primes that are Sophie Germain primes.

Crossrefs

Cf. A005384, (Sophie Germain primes), A128825, A338700, A339474, A339476, A339477, A339478.

Sequence in context: A213174 A256376 A128825 * A167573 A318356 A142790

Adjacent sequences: A339472 A339473 A339474 * A339476 A339477 A339478

Keyword

nonn

Author

Jon E. Schoenfield, Apr 24 2021

Status

approved