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A116538
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a(1)=1, a(2)=2; a(n) is the smallest positive integer not occurring earlier in the sequence such that gcd(a(n-2), a(n-1)+a(n)) = 1.
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1
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1, 2, 3, 4, 6, 5, 8, 9, 10, 7, 12, 11, 14, 13, 16, 15, 18, 19, 22, 17, 20, 21, 26, 24, 23, 30, 25, 28, 29, 32, 27, 34, 31, 36, 33, 38, 35, 40, 39, 42, 37, 46, 41, 44, 43, 48, 45, 50, 47, 52, 49, 54, 53, 56, 51, 58, 55, 60, 57, 62, 59, 64, 61, 66, 63, 68, 69, 70, 67, 72, 65, 74
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OFFSET
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1,2
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COMMENTS
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Sequence may be a permutation of the positive integers.
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LINKS
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EXAMPLE
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Among the positive integers not occurring among the first 6 terms of the sequence, 8 is the smallest m such that gcd(a(5), a(6)+m) = gcd(6,5+m) = 1.
Had we used 7 for m instead, we would have had gcd(6,5+7) = 6. So a(7) = 8.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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