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A280348
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Irregular triangle read by rows in which row n lists the divisors of the sum of the divisors of n.
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0
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1, 1, 3, 1, 2, 4, 1, 7, 1, 2, 3, 6, 1, 2, 3, 4, 6, 12, 1, 2, 4, 8, 1, 3, 5, 15, 1, 13, 1, 2, 3, 6, 9, 18, 1, 2, 3, 4, 6, 12, 1, 2, 4, 7, 14, 28, 1, 2, 7, 14, 1, 2, 3, 4, 6, 8, 12, 24, 1, 2, 3, 4, 6, 8, 12, 24, 1, 31, 1, 2, 3, 6, 9, 18, 1, 3, 13, 39, 1, 2, 4, 5, 10, 20, 1, 2, 3, 6, 7, 14, 21, 42, 1, 2, 4, 8, 16, 32, 1, 2, 3, 4, 6, 9, 12, 18, 36
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OFFSET
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1,3
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LINKS
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FORMULA
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EXAMPLE
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Triangle begins:
1;
1, 3;
1, 2, 4;
1, 7;
1, 2, 3, 6;
1, 2, 3, 4, 6, 12;
1, 2, 4, 8;
1, 3, 5, 15;
1, 13;
1, 2, 3, 6, 9, 18;
1, 2, 3, 4, 6, 12;
1, 2, 4, 7, 14, 28;
1, 2, 7, 14;
1, 2, 3, 4, 6, 8, 12, 24;
1, 2, 3, 4, 6, 8, 12, 24;
1, 31;
1, 2, 3, 6, 9, 18;
1, 3, 13, 39;
1, 2, 4, 5, 10, 20;
1, 2, 3, 6, 7, 14, 21, 42;
1, 2, 4, 8, 16, 32;
1, 2, 3, 4, 6, 9, 12, 18, 36;
1, 2, 3, 4, 6, 8, 12, 24;
1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60;
...
For n = 10 the sum of the divisors of 10 is 1 + 2 + 5 + 10 = 18, so row 10 of the triangle lists the divisors of 18: 1, 2, 3, 6, 9, 18.
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CROSSREFS
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KEYWORD
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nonn,tabf
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AUTHOR
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STATUS
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approved
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