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A074931 2-almost-primes equidistant from consecutive prime twin pairs. 0
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 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

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).

EXAMPLE

17 is OK because 3*17=51 is equidistant between {41,43} and {59,61}.

CROSSREFS

Cf. A001358, A001748, A074953.

Sequence in context: A181291 A038703 A163586 * A023226 A113169 A174913

Adjacent sequences:  A074928 A074929 A074930 * A074932 A074933 A074934

KEYWORD

nonn

AUTHOR

N. Fernandez, Zak Seidov (primeness(AT)borve.org; zakseidov(AT)yahoo.com), Oct 10 2002

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Last modified February 16 15:55 EST 2012. Contains 205933 sequences.