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Search: id:A059763
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| A059763 |
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Initial (unsafe) primes of Cunningham chains of first type with length exactly 4. Primes in A059453 which survive as primes just three "2p+1 iterations", forming chains of exactly 4 terms. |
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+0
13
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| 509, 1229, 1409, 2699, 3539, 6449, 10589, 11549, 11909, 12119, 17159, 19709, 19889, 22349, 26189, 27479, 30389, 43649, 55229, 57839, 60149, 71399, 74699, 75329, 82499, 87539, 98369, 101399, 104369
(list; graph; listen)
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OFFSET
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0,1
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FORMULA
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{(p-1)/2, p, 2p+1, 4p+3, 8p+7, 16p+15} = {composite, prime, prime, prime, prime, composite}
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EXAMPLE
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1229 is here because 614 and 16*1229+15=19679 are composite numbers, while {1229,2459,4919,9839} are primes.
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CROSSREFS
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A023272, A023302, A023330, A005384, A005385, A059452-A059455, A007700, A005602.
Sequence in context: A142819 A110025 A110023 this_sequence A126438 A126582 A062905
Adjacent sequences: A059760 A059761 A059762 this_sequence A059764 A059765 A059766
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Feb 20 2001
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