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

Offset: 1

Author

N. J. A. Sloane, Dec 07 2010

Keywords

• nonn
• more
• tabf

Examples

			Triangle begins:
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
		

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.

Crossrefs

Cf. A176431. A176463. Leading column is A176485.