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Search: id:A128468
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| A128468 |
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Numbers of the form 30k+17 or possible lower bounds of twin primes pairs ending in 7. |
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+0
1
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| 17, 47, 77, 107, 137, 167, 197, 227, 257, 287, 317, 347, 377, 407, 437, 467, 497, 527, 557, 587, 617, 647, 677, 707, 737, 767, 797, 827, 857, 887, 917, 947, 977, 1007, 1037, 1067, 1097, 1127, 1157, 1187, 1217, 1247, 1277, 1307, 1337, 1367, 1397, 1427, 1457
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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For a 30k+r "wheel", r = 11,17,29 are the only possible values that can form a a lower twin prime pair. The 30k+r wheel gives the recurrence 1, 7,11,13,17,19,23,29 31,37,41,43,47,49,53,59 .. which is frequently used in prime number sieves to skip multiples of 2,3,5. The fact that adding 2 to 30k+1,7,13,19,23 will gives us a multiple of 3 or 5, precludes these numbers from being a lower member of a twin prime pair. This leaves us with r = 11,17,29 as the only possible cases to form a lower bound of a twin prime pair.
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EXAMPLE
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17 = 30*0 + 17, the lower part of the twin prime pair 17,19.
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PROGRAM
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(PARI) g(n) = forstep(x=17, n, 30, print1(x", "))
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CROSSREFS
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Sequence in context: A126912 A051616 A061275 this_sequence A031374 A061722 A039949
Adjacent sequences: A128465 A128466 A128467 this_sequence A128469 A128470 A128471
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KEYWORD
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easy,nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)hotmail.com), May 05 2007
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