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A360010
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First part of the n-th weakly decreasing triple of positive integers sorted lexicographically. Each n > 0 is repeated A000217(n) times.
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3
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1, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8
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OFFSET
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1,2
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LINKS
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FORMULA
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Sum_{n>=1} (-1)^(n+1)/a(n) = Pi/8 + log(2)/4. - Amiram Eldar, Feb 18 2024
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EXAMPLE
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Triples begin: (1,1,1), (2,1,1), (2,2,1), (2,2,2), (3,1,1), (3,2,1), (3,2,2), (3,3,1), (3,3,2), (3,3,3), ...
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MATHEMATICA
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nn=9; First/@Select[Tuples[Range[nn], 3], GreaterEqual@@#&]
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CROSSREFS
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For pairs instead of triples we have A002024.
The second instead of first part is A194848.
The third instead of first part is A333516.
Concatenating all the triples gives A360240.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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