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Search: id:A064417
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| A064417 |
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a(1) = 1, a(2) = 2, a(3) = 3; for n >3 a(n) = smallest number not already used such that GCD{ a(n), a(n-1) } >= 3. |
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+0
2
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| 1, 2, 3, 6, 9, 12, 4, 8, 16, 20, 5, 10, 15, 18, 21, 7, 14, 28, 24, 27, 30, 25, 35, 40, 32, 36, 33, 11, 22, 44, 48, 39, 13, 26, 52, 56, 42, 45, 50, 55, 60, 51, 17, 34, 68, 64, 72, 54, 57, 19, 38, 76, 80, 65, 70, 49, 63, 66, 69, 23, 46, 92, 84, 75, 78, 81, 87, 29, 58, 116, 88, 77, 91
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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A permutation of the natural numbers.
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REFERENCES
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J. C. Lagarias, E. M. Rains and N. J. A. Sloane, Problem 10927, Amer. Math. Monthly, 109 (2002), 202; 111 (No. 2, 2004), 167-168.
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LINKS
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J. C. Lagarias, E. M. Rains and N. J. A. Sloane, The EKG sequence, Exper. Math. 11 (2002), 437-446.
Index entries for sequences related to EKG sequence
Index entries for sequences that are permutations of the natural numbers
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CROSSREFS
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Cf. A064413. A064956 gives inverse permutation.
Sequence in context: A032704 A029805 A082007 this_sequence A131975 A057474 A145441
Adjacent sequences: A064414 A064415 A064416 this_sequence A064418 A064419 A064420
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KEYWORD
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nonn,nice,easy
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AUTHOR
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Jonathan Ayres (Jonathan.ayres(AT)btinternet.com), Sep 30 2001
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EXTENSIONS
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More terms from Naohiro Nomoto (n_nomoto(AT)yabumi.com), Sep 30 2001
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