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A260819
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Positive integer solutions [a',b',c',d'] of the equation 1/a + 1/b + 1/c + 1/d = 1, for a <= b <= c <= d, lexicographically sorted.
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2
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2, 3, 7, 42, 2, 3, 8, 24, 2, 3, 9, 18, 2, 3, 10, 15, 2, 3, 12, 12, 2, 4, 5, 20, 2, 4, 6, 12, 2, 4, 8, 8, 2, 5, 5, 10, 2, 6, 6, 6, 3, 3, 4, 12, 3, 3, 6, 6, 3, 4, 4, 6, 4, 4, 4, 4
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OFFSET
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1,1
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COMMENTS
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There are only 14 positive integer solutions for 1/a + 1/b + 1/c + 1/d = 1.
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REFERENCES
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W. Sierpiński, 250 problems in elementary number theory, Elsevier Science Ltd, pages 14 and 83-85.
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LINKS
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EXAMPLE
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The 2nd row is [2,3,8,24] and represents the solution 1/2 + 1/3 + 1/8 + 1/24 = 1.
List of all the solutions:
1/2 + 1/3 + 1/7 + 1/42 = 1
1/2 + 1/3 + 1/8 + 1/24 = 1
1/2 + 1/3 + 1/9 + 1/18 = 1
1/2 + 1/3 + 1/10 + 1/15 = 1
1/2 + 1/3 + 1/12 + 1/12 = 1
1/2 + 1/4 + 1/5 + 1/20 = 1
1/2 + 1/4 + 1/6 + 1/12 = 1
1/2 + 1/4 + 1/8 + 1/8 = 1
1/2 + 1/5 + 1/5 + 1/10 = 1
1/2 + 1/6 + 1/6 + 1/6 = 1
1/3 + 1/3 + 1/4 + 1/12 = 1
1/3 + 1/3 + 1/6 + 1/6 = 1
1/3 + 1/4 + 1/4 + 1/6 = 1
1/4 + 1/4 + 1/4 + 1/4 = 1
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CROSSREFS
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KEYWORD
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easy,full,fini,nonn,tabf
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AUTHOR
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STATUS
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approved
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