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Search: id:A087820
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| A087820 |
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Primes P of the form P=(j*P(i)#)/2 - 2 such that P+4 is the next prime, where j is odd, 0 < j < P(i+1), P(i) = i-th prime, P(i)# = i-th primorial (A002110). |
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+0
4
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| 7, 13, 43, 103, 313, 3463, 15013, 195193, 225223, 765763, 4339333, 3011753743, 9704539843, 100280245063, 2707566616753, 124286232650865283, 150451755314205343, 10760571195298599673, 211829530101735290743
(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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(27*2*3*5*7*11*13*17*19*23)/2 - 2 = 3011753743 and (27*2*3*5*7*11*13*17*19*23)/2 + 2 = 3011753747 are gap 4 primes, so j=27, i=9, P(i)=23.
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CROSSREFS
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Cf. A087821, A087822, etc.
Sequence in context: A151781 A047977 A139403 this_sequence A166945 A023286 A159305
Adjacent sequences: A087817 A087818 A087819 this_sequence A087821 A087822 A087823
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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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More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 19 2003
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