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Search: id:A138153
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| A138153 |
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If the numbers a(1)...a(n) contain a hole, then a(n+1) is the smallest hole; otherwise a(n+1) = a(n-2) + a(n-1) + a(n). |
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3
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| 1, 2, 3, 5, 4, 12, 6, 7, 8, 9, 10, 11, 30, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 84, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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This is to A060000 as tribonacci A000073 is to Fibonacci A000045. Let H be the set of positive numbers less than a(n) which are not equal to some a(i), i < n. This H is the 'set of holes so far'. If H is nonempty, then define a(n+1) = minimum(H). Otherwise define a(n+1) = a(n-2) + a(n-1) + a(n). Permutation of the natural numbers with inverse not yet in the OEIS. The new record highs reached in the sequence (analogous to A060013) begin 1, 2, 3, 5, 12, 30, 84, 246. Note that 30 = 3*12-6, 84 = 3*30-6, 246 = 3*84-6.
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CROSSREFS
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Cf. A000040, A000073, A060000, A060013.
Sequence in context: A079521 A112060 A084933 this_sequence A023395 A101409 A131401
Adjacent sequences: A138150 A138151 A138152 this_sequence A138154 A138155 A138156
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), May 04 2008
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