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A092125
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Numbers n such that n, n+2, n+4 are semiprimes.
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9
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91, 119, 141, 183, 201, 213, 215, 217, 287, 299, 301, 319, 391, 411, 413, 469, 515, 533, 579, 667, 685, 695, 789, 813, 1055, 1077, 1133, 1135, 1137, 1145, 1165, 1203, 1253, 1313, 1343, 1345, 1347, 1383, 1385, 1387, 1389, 1401, 1561, 1639, 1685, 1687, 1761
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Semiprimes in arithmetic progression. All terms are odd, see also A056809.
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MATHEMATICA
| PrimeFactorExponentsAdded[n_] := Plus @@ Flatten[Table[ #[[2]], {1}] & /@ FactorInteger[n]]; Select[ Range[ 1792], PrimeFactorExponentsAdded[ # ] == PrimeFactorExponentsAdded[ # + 2] == PrimeFactorExponentsAdded[ # + 4] == 2 &] (from Robert G. Wilson v Feb 24 2004)
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PROG
| (MAGMA)IsSemiprime:=func< n| &+[ k[2]: k in Factorization(n) ] eq 2 >; [ n: n in [2..4300]|IsSemiprime(n) and IsSemiprime(n+2) and IsSemiprime(n+4)] [From Vincenzo Librandi, Dec 16 2010]
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CROSSREFS
| Cf. A056809, A070552, A092126, A092127, A092128, A092129.
Sequence in context: A161945 A140389 A157345 * A005935 A020307 A020235
Adjacent sequences: A092122 A092123 A092124 * A092126 A092127 A092128
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KEYWORD
| easy,nonn
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AUTHOR
| Zak Seidov (zakseidov(AT)yahoo.com), Feb 22 2004
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