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Search: id:A110093
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| A110093 |
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Smallest prime ending (through <*2+1>) or/and <*2-1>) a complete Cunningham chain (of the first or the second kind) of length n. |
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1
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OFFSET
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1,1
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COMMENT
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The word "complete" indicates each chain is exactly n primes long for the operator in function (i.e. the chain cannot be a subchain of another one); but the first and/or last term may be involved in a chain of the other kind (i.e. the chain may be connected to another one).
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LINKS
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Chris Caldwell's Prime Glossary, Cunningham chains.
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EXAMPLE
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a(1)=11 because 2, 3, 5 and 7 are not ending chains; or are part of chains longer than one prime; 11, although is part of a five primes <2p+1> chain, is isolated through <2p-1>.
a(2)=7 because 7 ends through <2p+1> the first two primes chain: 3->7 (even if both primes are also part of <2p-1> chains).
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MAPLE
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Terms computed by Gilles Sadowski
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CROSSREFS
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Cf. A023272, A023302, A023330, A005384, A005385, A059452, A059455, A007700, Cf. A059759, A059760, A059761, A059762, A059763, A059764, A059765, A038397, A104349, A091314, A069362, A016093, A014937, A057326, A110059, A110056, A110038, A059766, A110027, A059764, A110025, A110024, A059763, A110022, A109998, A109946, A109927, A109835, A109828.
Sequence in context: A155914 A087896 A144262 this_sequence A166521 A060954 A038321
Adjacent sequences: A110090 A110091 A110092 this_sequence A110094 A110095 A110096
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KEYWORD
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easy,nonn
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AUTHOR
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Alexandre Wajnberg (alexandre.wajnberg(AT)ulb.ac.be), Sep 04 2005
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