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A367219
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Number of integer partitions of n whose length cannot be written as a nonnegative linear combination of the distinct parts.
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24
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0, 0, 1, 1, 1, 1, 3, 2, 4, 4, 7, 6, 11, 9, 16, 16, 23, 22, 35, 33, 48, 50, 69, 70, 99, 99, 136, 142, 187, 194, 261, 267, 346, 367, 468, 489, 626, 650, 824, 870, 1081, 1135, 1421, 1485, 1833, 1942, 2374, 2501, 3062, 3220, 3915, 4145, 4987, 5274, 6363, 6709, 8027
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OFFSET
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0,7
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LINKS
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EXAMPLE
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3 cannot be written as a nonnegative linear combination of 2 and 5, so (5,2,2) is counted under a(9).
The a(2) = 1 through a(10) = 7 partitions:
(2) (3) (4) (5) (6) (7) (8) (9) (10)
(3,3) (4,3) (4,4) (5,4) (5,5)
(2,2,2) (5,3) (6,3) (6,4)
(4,2,2) (5,2,2) (7,3)
(4,4,2)
(6,2,2)
(2,2,2,2,2)
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MATHEMATICA
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combs[n_, y_]:=With[{s=Table[{k, i}, {k, y}, {i, 0, Floor[n/k]}]}, Select[Tuples[s], Total[Times@@@#]==n&]];
Table[Length[Select[IntegerPartitions[n], combs[Length[#], Union[#]]=={}&]], {n, 0, 15}]
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CROSSREFS
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The following sequences count and rank integer partitions and finite sets according to whether their length is a subset-sum or linear combination of the parts. The current sequence is starred.
sum-full sum-free comb-full comb-free
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A124506 appears to count combination-free subsets, differences of A326083.
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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