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Search: id:A077553
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| A077553 |
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Triangle in which the n-th row contains n distinct composite numbers with the least product and has least number of prime divisors. No member of a row is a multiple of another member of the row. |
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5
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| 4, 4, 6, 4, 6, 9, 4, 6, 9, 10, 4, 6, 9, 10, 15, 4, 6, 9, 10, 15, 25, 4, 6, 9, 10, 14, 15, 21, 4, 6, 9, 10, 14, 15, 21, 25, 4, 6, 9, 10, 14, 15, 21, 25, 35, 4, 6, 9, 10, 14, 15, 21, 25, 35, 49, 4, 6, 9, 10, 14, 15, 21, 22, 25, 33, 35, 4, 6, 9, 10, 14, 15, 21, 22, 25, 33, 35, 49, 4, 6, 9, 10
(list; table; graph; listen)
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OFFSET
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0,1
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COMMENT
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If there are two sets of distinct composite numbers satisfying the above condition then the set with lesser product is chosen irrespective of the number of prime divisors. Perhaps the ambiguity may not arise. E.g. Row 6 is 4,6,9,10,15,25. This row can not be extended to get the next row without bringing in another prime because every number divisible by 2,3 or 5 will be a multiple of one of the previous terms. Hence in row 7, prime 7 has to be brought in and then we get a new set of numbers 4,6,9,10,14,15,21.
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LINKS
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Tanya Khovanova, Recursive Sequences
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EXAMPLE
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4;
4,6;
4,6,9;
4,6,9,10;
4,6,9,10,15;
4,6,9,10,15,25;
4,6,9,10,14,15,21;
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CROSSREFS
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Cf. A001358, A077554, A077555, A087112, A005843.
Adjacent sequences: A077550 A077551 A077552 this_sequence A077554 A077555 A077556
Sequence in context: A021228 A059656 A064041 this_sequence A010659 A131089 A066560
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KEYWORD
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nonn,tabl
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Nov 10 2002
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EXTENSIONS
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More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 21 2003
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