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Search: id:A106252
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| A106252 |
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Number of positive integer triples (x,y,z), with x<=y<=z<=n, such that each of x,y,and z divides the sum of the other two. |
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+0
2
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| 1, 3, 5, 7, 8, 11, 12, 14, 16, 18, 19, 22, 23, 25, 27, 29, 30, 33, 34, 36, 38, 40, 41, 44, 45, 47, 49, 51, 52, 55, 56, 58, 60, 62, 63, 66, 67, 69, 71, 73, 74, 77, 78, 80, 82, 84, 85, 88, 89, 91, 93, 95, 96, 99, 100, 102, 104, 106, 107, 110, 111, 113, 115, 117, 118, 121, 122
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OFFSET
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1,2
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COMMENT
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The following conjecture is probably not very difficult: Conjecture. The sequence (A106253) of differences of this sequence is periodic with period 6.
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EXAMPLE
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(1,1,1), (1,1,2), (1,2,3), (2,2,2), and (3,3,3) are the triples that have the desired property for n=3, so a(3)=5.
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CROSSREFS
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Cf. A106253.
Sequence in context: A003144 A024977 A088759 this_sequence A050111 A090542 A047485
Adjacent sequences: A106249 A106250 A106251 this_sequence A106253 A106254 A106255
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KEYWORD
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nonn
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AUTHOR
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John W. Layman (layman(AT)math.vt.edu), Apr 27 2005
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