A074931 Primes p such that 3p is equidistant from consecutive prime twin pairs.

3, 5, 17, 29, 41, 71, 149, 281, 317, 347, 359, 397, 647, 751, 787, 857, 907, 1093, 1279, 1381, 1511, 1531, 1663, 1783, 2447, 2683, 2803, 3271, 3323, 4019, 4153, 4513, 4567, 4639, 5557, 5647, 5801, 5923, 6599, 6659, 6911, 7013, 7573, 7883, 9187, 9257, 9431

Offset: 1

Author

N. Fernandez (primeness(AT)borve.org), Zak Seidov, Oct 10 2002

Keywords

• nonn

Comments

Numbers equidistant from consecutive twins (see A074953) are multiples of 3 and they may be almost primes only of form 3*prime. In the sequence, these primes are given. Also: A001748 (3*prime 2-almost-primes) and A001358 (all 2-almost-primes).

Examples

			17 is in the sequence because 3 * 17 = 51 is equidistant between {41, 43} and {59, 61}.
19 is not in the sequence because 3 * 19 = 57, which is much closer to {59, 61} than to {41, 43}.
		

Crossrefs

Cf. A001358, A001748, A074953.

Extensions

New name from Charles R Greathouse IV, Oct 12 2013