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Search: id:A027751
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| A027751 |
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Triangle read by rows in which row n lists the proper divisors of n (those divisors of n which are < n), with the first row {1} by convention. |
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4
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| 1, 1, 1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 4, 1, 3, 1, 2, 5, 1, 1, 2, 3, 4, 6, 1, 1, 2, 7, 1, 3, 5, 1, 2, 4, 8, 1, 1, 2, 3, 6, 9, 1, 1, 2, 4, 5, 10, 1, 3, 7, 1, 2, 11, 1, 1, 2, 3, 4, 6, 8, 12, 1, 5, 1, 2, 13, 1, 3, 9, 1, 2, 4, 7, 14, 1, 1, 2, 3, 5, 6, 10, 15, 1, 1, 2, 4, 8, 16, 1, 3, 11, 1, 2, 17, 1, 5, 7, 1, 2, 3, 4, 6, 9, 12, 18
(list; graph; listen)
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OFFSET
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1,5
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COMMENT
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Or, take the list 1,2,3,4,... of natural numbers (A000027) and replace each number by its proper divisors.
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EXAMPLE
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1->1; 2->1; 3->1; 4->1,2; 5->1; 6->1,2,3; so sequence begins 1,1,1,1,2,1,1,2,3...
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CROSSREFS
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Cf. A027750, A032741, A001065, A000005.
Sequence in context: A128227 A140207 A104763 this_sequence A004070 A048887 A047913
Adjacent sequences: A027748 A027749 A027750 this_sequence A027752 A027753 A027754
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KEYWORD
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nonn,easy,tabf
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AUTHOR
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njas
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EXTENSIONS
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More terms from Patrick De Geest (pdg(AT)worldofnumbers.com), May 15 1998.
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