|
|
A074931
|
|
Primes p such that 3p is 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;
text;
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).
|
|
LINKS
|
|
|
EXAMPLE
|
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
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
N. Fernandez (primeness(AT)borve.org), Zak Seidov, Oct 10 2002
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|