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Search: id:A129926
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| A129926 |
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Semiprimes n such that 3*n - 2 is a prime. |
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1
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| 15, 21, 25, 33, 35, 51, 55, 65, 77, 91, 93, 95, 111, 123, 133, 141, 145, 155, 183, 201, 203, 205, 215, 221, 237, 247, 253, 287, 295, 303, 323, 341, 355, 365, 377, 391, 411, 413, 417, 427, 485, 497, 511, 515, 517, 527, 533, 537, 543, 553, 565, 581, 583, 597
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Indices of 3-almost prime octagonal numbers.
Subset of A001358. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 07 2007
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MAPLE
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isA001358 := proc(n) if numtheory[bigomega](n) = 2 then true ; else false ; end ; end: isA129926 := proc(n) if isA001358(n) then isprime(3*n-2) ; else false ; fi ; end: for n from 1 to 1000 do if isA129926(n) then printf("%d, ", n) ; fi ; od ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 07 2007
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CROSSREFS
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Sequence in context: A033708 A154545 A156063 this_sequence A020204 A057489 A070811
Adjacent sequences: A129923 A129924 A129925 this_sequence A129927 A129928 A129929
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KEYWORD
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nonn
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AUTHOR
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Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Jun 06 2007
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 07 2007
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