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A176463
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Irregular triangle read by rows: T(n,k) = number of Huffman-equivalence classes of ternary trees with 3n+1 leaves and 4k leaves on the bottom level (n>=1, k>=1).
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3
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1, 1, 1, 1, 2, 1, 1, 4, 2, 1, 1, 8, 4, 2, 1, 15, 8, 4, 2, 29, 15, 8, 4, 1, 57, 29, 15, 8, 2, 1, 112, 57, 29, 15, 4, 2, 1, 220, 112, 57, 29, 7, 4, 2
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OFFSET
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1,5
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REFERENCES
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J. Paschke et al., Computing and estimating the number of n-ary Huffman sequences of a specified length, Discrete Math., 311 (2011), 1-7.
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LINKS
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Table of n, a(n) for n=1..44.
Christian Elsholtz, Clemens Heuberger, Helmut Prodinger, The number of Huffman codes, compact trees, and sums of unit fractions, arXiv:1108.5964v1 [math.CO], Aug 30, 2011. Also IEEE Trans. Information Theory, Vol. 59, No. 2, 2013 pp. 1065-1075.
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EXAMPLE
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Triangle begins:
1
1
1 1
2 1 1
4 2 1 1
8 4 2 1
15 8 4 2
29 15 8 4 1
57 29 15 8 2 1
112 57 29 15 4 2 1
220 112 57 29 7 4 2
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CROSSREFS
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Cf. A176431, A176452, A194628 - A194633. Leading column gives A176503.
Sequence in context: A152568 A155038 A057728 * A098050 A278984 A111579
Adjacent sequences: A176460 A176461 A176462 * A176464 A176465 A176466
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KEYWORD
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nonn,tabf
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AUTHOR
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N. J. A. Sloane, Dec 07 2010
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STATUS
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approved
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