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A176463 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). 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

REFERENCES

J. Paschke et al., Computing and estimating the number of n-ary Huffman sequences of a specified length, Discrete Math., 311 (2011), 1-7.

LINKS

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.

EXAMPLE

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

CROSSREFS

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

KEYWORD

nonn,tabf

AUTHOR

N. J. A. Sloane, Dec 07 2010

STATUS

approved

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Last modified January 27 15:14 EST 2020. Contains 331295 sequences. (Running on oeis4.)