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A066182
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Permutation of the integers with cycle form {1}, {3, 2}, {6, 5, 4}, {10, 9, 8, 7}, ...
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4
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1, 3, 2, 6, 4, 5, 10, 7, 8, 9, 15, 11, 12, 13, 14, 21, 16, 17, 18, 19, 20, 28, 22, 23, 24, 25, 26, 27, 36, 29, 30, 31, 32, 33, 34, 35, 45, 37, 38, 39, 40, 41, 42, 43, 44, 55, 46, 47, 48, 49, 50, 51, 52, 53, 54, 66, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 78, 67, 68, 69, 70, 71
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OFFSET
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1,2
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COMMENTS
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Arrange natural numbers 1,2,3,4,5,... as a triangle like A000027, then rotate each row of triangle one step right. - Antti Karttunen, May 07 2002
As a rectangular array, a(n) is the natural interspersion of the sequence of triangular numbers; see A192872. [Clark Kimberling, Aug 12 2011]
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LINKS
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FORMULA
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EXAMPLE
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Northwest corner, when sequence is formatted as the natural interspersion of the sequence (1,3,6,10,15,...) of triangular numbers:
1...3...6...10...15
2...4...7...11...16
5...8...12..17...23
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MATHEMATICA
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FromCycles[Table[n(n-1)/2+Range[n, 1, -1], {n, 13}]]
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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