A383468 Semiprimes s = A001358(k) such that k, s - k and s + k are also semiprimes.
10, 15, 141, 166, 274, 298, 299, 687, 995, 1115, 1227, 1299, 1345, 1891, 1945, 2194, 2661, 2998, 3093, 3287, 3566, 3781, 3902, 4174, 4262, 4497, 4798, 5378, 5414, 5758, 6609, 7094, 7666, 8354, 8434, 9566, 10041, 10342, 11051, 11091, 11486, 11582, 11702, 12279, 12574, 13154, 13346, 13387, 13466
Offset: 1
Keywords
Examples
a(3) = 141 is a term because 141 = 3 * 47 = A001358(46) is a semiprime and 46 = 2 * 23, 141 - 46 = 95 = 5 * 19 and 141 + 46 = 187 = 11 * 17 are all semiprimes.
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
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Maple
k:= 0: R:= NULL: count:= 0: for s from 1 while count < 100 do if numtheory:-bigomega(s) = 2 then k:= k+1; if andmap(t -> numtheory:-bigomega(t) = 2, [k, s-k, s+k]) then R:= R, s; count:= count+1; fi fi; od: R;
Comments