A176452 - OEIS

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A176452

Irregular triangle read by rows: T(n,k) = number of Huffman-equivalence classes of ternary trees with 2n+1 leaves and 3k leaves on the bottom level (n>=1, k>=1).

1, 1, 1, 1, 2, 1, 1, 4, 2, 1, 7, 4, 2, 13, 7, 4, 1, 25, 13, 7, 2, 1, 48, 25, 13, 3, 2, 1, 92, 48, 25, 6, 3, 2, 176, 92, 48, 12, 6, 3, 1, 338, 176, 92, 23, 12, 6, 1

(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..48.

EXAMPLE

Triangle begins:

1 1

2 1 1

4 2 1

7 4 2

13 7 4 1

25 13 7 2 1

48 25 13 3 2 1

92 48 25 6 3 2

176 92 48 12 6 3 1

338 176 92 23 12 6 1

CROSSREFS

Cf. A176431. A176463. Leading column is A176485.

Sequence in context: A122773 A029268 A347629 * A244581 A064191 A127420

Adjacent sequences: A176449 A176450 A176451 * A176453 A176454 A176455

KEYWORD

nonn,more,tabf

AUTHOR

N. J. A. Sloane, Dec 07 2010

STATUS

approved