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Search: id:A136405
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| A136405 |
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Array read by rows: T(n,k) is the number of bi-partitions of the pair (n,k) into pairs (n_i,k_i) of positive integers such that sum k_i = k and sum n_i.k_i = n. |
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1
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| 1, 1, 2, 1, 1, 3, 1, 3, 2, 5, 1, 2, 4, 3, 7, 1, 4, 6, 7, 5, 11, 1, 3, 7, 8, 11, 7, 15, 1, 5, 8, 16, 14, 17, 11, 22, 1, 4, 12, 14, 23, 21, 25, 15, 30, 1, 6, 12, 24, 29, 38, 33, 37, 22, 42, 1
(list; table; graph; listen)
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OFFSET
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1,3
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COMMENT
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T(n,1) = 1, T(n,2) = A028242(n) and T(n,n) = A000041(n).
Row sums: A006171.
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EXAMPLE
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T(4,2) = 3 since (4,2) can be bi-partitioned as (2,2) or ((1,1),(3,1)) or ((2,1),(2,1)).
T(5,3) = 4 since (5,3) can be bi-partitioned as ((1,1),(2,2)) or ((3,1),(1,2)) or ((1,1),(1,1),(3,1)) or ((1,1),(2,1),(2,1)).
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CROSSREFS
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Cf. A090806.
Sequence in context: A029288 A050117 A121560 this_sequence A035667 A102426 A092865
Adjacent sequences: A136402 A136403 A136404 this_sequence A136406 A136407 A136408
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KEYWORD
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nonn,tabl
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AUTHOR
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Benoit Jubin (benoit_jubin(AT)yahoo.fr), Apr 13 2008, Apr 22 2008, May 17 2008
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