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Search: id:A103683
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| A103683 |
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a(1)=1, a(2)=2, a(3)=3, a(n) = smallest positive integer not occurring earlier in sequence and coprime to a(n-1), a(n-2) and a(n-3). |
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+0
2
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| 1, 2, 3, 5, 7, 4, 9, 11, 13, 8, 15, 17, 19, 14, 23, 25, 27, 16, 29, 31, 21, 10, 37, 41, 33, 20, 43, 47, 39, 22, 35, 53, 51, 26, 49, 55, 57, 32, 59, 61, 45, 28, 67, 71, 65, 6, 73, 77, 79, 12, 83, 85, 89, 18, 91, 95, 97, 24, 101, 103, 107, 30, 109, 113, 119, 36, 115, 121, 127, 34
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Conjectured to be a permutation of the natural numbers.
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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MATHEMATICA
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t = Range[200]; a[1] = 1; a[2] = 2; a[3] = 3; a[n_] := a[n] = Block[{c = Complement[t, Table[a[i], {i, n - 1}]], k = 1}, While[ Union[ GCD[ c[[k]], {a[n - 1], a[n - 2], a[n - 3]}]] != {1}, k++ ]; c[[k]]]; Table[ a[n], {n, 70}] (from Robert G. Wilson v Mar 30 2005)
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CROSSREFS
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Cf. A084937. Inverse is in A105214.
Sequence in context: A140528 A065037 A101438 this_sequence A125151 A103866 A080164
Adjacent sequences: A103680 A103681 A103682 this_sequence A103684 A103685 A103686
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Mar 26 2005
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 30 2005
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