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Search: id:A108172
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| A108172 |
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Semiprimes p*q where p is a prime of the form 6n+1 (A002476) and q is a prime of the form 6n-1 (A007528). |
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+0
4
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| 35, 65, 77, 95, 119, 143, 155, 161, 185, 203, 209, 215, 221, 287, 299, 305, 323, 329, 335, 341, 365, 371, 377, 395, 407, 413, 437, 473, 485, 497, 515, 527, 533, 545, 551, 581, 611, 623, 629, 635, 671, 689, 695, 707, 713, 731, 737, 749, 755, 767, 779, 785
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Also semiprimes of the form 6n-1 (or 6n+5).
Every semiprime not divisible by 2 or 3 must be in one of these three disjoint sets:
A108164 - the product of two primes of the form 6n+1 (A002476),
A108166 - the product of two primes of the form 6n-1 (A007528),
A108172 - the product of a prime of the form 6n+1 and a prime of the form 6n-1.
The product of a prime of the form 6n+1 and a prime of the form 6n-1 is a semiprime of the form 6n-1.
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REFERENCES
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M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 870.
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LINKS
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M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, December 1972 [alternative scanned copy].
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FORMULA
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a(n) = 6 * A112776(n) + 5.
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CROSSREFS
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Cf. A001358, A002476, A007528.
Sequence in context: A095958 A026064 A092256 this_sequence A135802 A043390 A031481
Adjacent sequences: A108169 A108170 A108171 this_sequence A108173 A108174 A108175
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost2(AT)yahoo.com), Jun 13 2005
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EXTENSIONS
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Edited by Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 15 2005
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