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Search: id:A134001
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| A134001 |
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Array read by anti-diagonals: row n contains the positive integers each with exactly n positive "isolated divisors". A divisor, k, of n is isolated if neither (k-1) nor (k+1) divides n. |
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+0
2
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| 3, 9, 5, 15, 16, 7, 36, 21, 18, 8, 45, 54, 24, 25, 10, 126, 48, 64, 27, 30, 11, 96, 150, 60, 66, 28, 42, 12, 144, 105, 162, 63, 78, 32, 49, 13, 120, 168, 108, 196, 70, 81, 33, 121, 14, 324, 180, 198, 135, 256, 72, 90, 35, 169, 17, 240, 378, 192, 225, 140, 294, 75, 100, 39
(list; table; graph; listen)
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OFFSET
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2,1
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COMMENT
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The left column (column 1) of the array is sequence A133997. The array starts at column 1 and row 2. The only positive integers each with exactly 1 isolated divisor are 1,4,6.
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EXAMPLE
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2 isolated divisors: 3, 5, 7, 8,10,...
3 isolated divisors: 9,16,18,25,...
4 isolated divisors: 15,21,24,...
etc.
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CROSSREFS
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Cf. A134000, A133997.
Adjacent sequences: A133998 A133999 A134000 this_sequence A134002 A134003 A134004
Sequence in context: A129145 A064471 A054509 this_sequence A088898 A143218 A103934
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KEYWORD
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nonn,tabl
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Oct 01 2007
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jun 25 2008
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