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Search: id:A126260
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| A126260 |
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Irregular triangle read by rows where row n contains the positive integers k, k<=n, where every positive integer <=k and coprime to k is also coprime to n. |
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+0
6
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| 1, 1, 2, 1, 2, 3, 1, 2, 4, 1, 2, 3, 4, 5, 1, 2, 6, 1, 2, 3, 4, 5, 6, 7, 1, 2, 4, 6, 8, 1, 2, 3, 6, 9, 1, 2, 4, 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1, 2, 6, 12, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 1, 2, 4, 6, 14, 1, 2, 3, 15, 1, 2, 4, 6, 8, 10, 12, 14, 16, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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The first term of each row is 1. The second term of each row, except for row 1, is 2. The last term of row n is n.
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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Table begins:
1
1,2
1,2,3
1,2,4
1,2,3,4,5
1,2,6
...
Row 10 is (1,2,4,10) because the positive integers <=1 and coprime to 1 are {1}, for 2 they are {1}, for 4 they are {1,3}, for 10 they are {1,3,7, 9}; and 1,1,1,3,1,3,7,9 are each coprime to 10.
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MATHEMATICA
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f[n_] := Select[Range[n], GCD[ #, n] == 1 &]; g[n_] := Select[Range[n], Times @@ GCD[f[ # ], n] == 1 &]; Flatten@Table[g[n], {n, 17}] (*Chandler*)
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CROSSREFS
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Sequence in context: A092080 A165884 A136311 this_sequence A163491 A080772 A145111
Adjacent sequences: A126257 A126258 A126259 this_sequence A126261 A126262 A126263
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KEYWORD
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nonn,tabf
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AUTHOR
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Leroy Quet Dec 22 2006
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Dec 24 2006
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