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Search: id:A087821
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| A087821 |
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Sequence of primes P(i) such that P=(j*P(i)#)/2 - 2 and P+4 are consecutive primes, where j is odd, 0 < j < P(i+1) and P(i) denotes i-th prime. |
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3
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| 3, 5, 5, 7, 7, 11, 13, 13, 13, 17, 17, 23, 29, 31, 31, 43, 43, 47, 53, 53, 61, 73, 83, 89, 89, 103, 131, 131, 173, 223, 227, 241, 251, 257, 311, 331, 359, 443, 523
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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I think I have a proof that the sequence is infinite.
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EXAMPLE
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(3*2*3*5*7*11*13*17)/2 - 2 = 765763 and (3*2*3*5*7*11*13*17)/2 + 2 = 765767 are gap 4 primes, with j=3, i=7, P(i)=17.
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CROSSREFS
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Cf. A087820, A087822.
Sequence in context: A112276 A079578 A066169 this_sequence A109258 A088081 A138475
Adjacent sequences: A087818 A087819 A087820 this_sequence A087822 A087823 A087824
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KEYWORD
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nonn
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AUTHOR
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Pierre CAMI (colettecami(AT)aol.com), Oct 06 2003
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EXTENSIONS
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Edited by Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 19 2003
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