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Search: id:A117108
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| A117108 |
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Moebius transform of tetrahedral numbers. |
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+0
1
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| 1, 3, 9, 16, 34, 43, 83, 100, 155, 182, 285, 292, 454, 473, 636, 696, 968, 929, 1329, 1304, 1678, 1735, 2299, 2136, 2890, 2818, 3489, 3484, 4494, 4052, 5455, 5168, 6250, 6168, 7652, 6988, 9138, 8547, 10196, 9840, 12340, 10954, 14189, 13140, 15380
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Partial sums of a(n) give A015634(n)
See also A116963, inverse Moebius transform of tetrahedral numbers. - Jonathan Vos Post (jvospost3(AT)gmail.com), Apr 20 2006
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FORMULA
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a(n)=|{(x,y,z) : 1<=x<=y<=z<=n, gcd(x,y,z,n)=1}|
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EXAMPLE
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a(2)=3 because of the triples (1,1,1), (1,1,2), (1,2,2)
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CROSSREFS
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Sequence in context: A024385 A061942 A058538 this_sequence A145796 A056403 A106676
Adjacent sequences: A117105 A117106 A117107 this_sequence A117109 A117110 A117111
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KEYWORD
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nonn
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AUTHOR
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Steve Butler (sbutler(AT)math.ucsd.edu), Apr 18 2006
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