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editing
proposed
editing
proposed
editing
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allocated for Ilya Gutkovskiy
Number of subsets of {1..n} whose arithmetic and harmonic means are both integers.
1, 2, 3, 4, 5, 8, 9, 10, 11, 13, 14, 18, 19, 21, 27, 28, 29, 48, 49, 71, 75, 78, 79, 103
1,2
a(6) = 8 subsets: {1}, {2}, {3}, {4}, {5}, {6}, {2, 6} and {1, 2, 3, 6}.
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nonn,more
Ilya Gutkovskiy, Dec 09 2024
approved
editing
allocated for Ilya Gutkovskiy
allocated
approved
allocated for Ilya Gutkovskiy
Number of compositions (ordered partitions) of n into distinct squarefree divisors of n.
1, 1, 1, 1, 0, 1, 7, 1, 0, 0, 1, 1, 24, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 0, 1, 0, 0, 1, 151, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 31, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 864, 1, 1, 0, 0, 1, 127, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 7, 1, 0
0,7
a(6) = 7 because we have [6], [3, 2, 1], [3, 1, 2], [2, 3, 1], [2, 1, 3], [1, 3, 2] and [1, 2, 3].
a(12) = 24 because we have [6, 3, 2, 1] and 4! = 24 permutations.
allocated
nonn
Ilya Gutkovskiy, Dec 09 2024
approved
editing
allocated for Ilya Gutkovskiy
allocated
approved
allocated for Ilya Gutkovskiy
Number of compositions (ordered partitions) of n into reciprocals of positive integers <= n.
1, 5, 154, 127459
1,2
a(2) = 5 because we have [1/2, 1/2, 1/2, 1/2], [1/2, 1/2, 1], [1/2, 1, 1/2], [1, 1/2, 1/2] and [1, 1].
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nonn,more
Ilya Gutkovskiy, Dec 09 2024
approved
editing
allocated for Ilya Gutkovskiy
allocated
approved
editing
proposed