A176431 - cp's OEIS frontend

A176431 Irregular triangle read by rows: T(n,k) = number of Huffman-equivalence classes of binary trees with n leaves and 2k leaves on the bottom level (n>=2, k>=1).

n	a(n)
2	1
3	1
4	1
5	1
6	2
7	1
8	3
9	2
10	5
11	3
12	1
13	9
14	5
15	1
16	1
17	16
18	9
19	2
20	1
21	28
22	16
23	4
24	2
25	50
26	28
27	7
28	4
29	89
30	50
31	12
32	7
33	1
34	159
35	89
36	22
37	12
38	2
39	1
40	285
41	159
42	39
43	22
44	3
45	2
46	510
47	285
48	70
49	39
50	22
51	3
52	1

[1, 1, 1, 1, 2, 1, 3, 2, 5, 3, 1, 9, 5, 1, 1, 16, 9, 2, 1, 28, 16, 4, 2, 50, 28, 7, 4, 89, 50, 12, 7, 1, 159, 89, 22, 12, 2, 1, 285, 159, 39, 22, 3, 2, 510, 285, 70, 39, 22, 3, 1]

cp's OEIS Frontend

A176431 Irregular triangle read by rows: T(n,k) = number of Huffman-equivalence classes of binary trees with n leaves and 2k leaves on the bottom level (n>=2, k>=1).

Table of values

List of values

n	a(n)
2	1
3	1
4	1
5	1
6	2
7	1
8	3
9	2
10	5
11	3
12	1
13	9
14	5
15	1
16	1
17	16
18	9
19	2
20	1
21	28
22	16
23	4
24	2
25	50
26	28
27	7
28	4
29	89
30	50
31	12
32	7
33	1
34	159
35	89
36	22
37	12
38	2
39	1
40	285
41	159
42	39
43	22
44	3
45	2
46	510
47	285
48	70
49	39
50	22
51	3
52	1

n	a(n)
2	1
3	1
4	1
5	1
6	2
7	1
8	3
9	2
10	5
11	3
12	1
13	9
14	5
15	1
16	1
17	16
18	9
19	2
20	1
21	28
22	16
23	4
24	2
25	50
26	28
27	7
28	4
29	89
30	50
31	12
32	7
33	1
34	159
35	89
36	22
37	12
38	2
39	1
40	285
41	159
42	39
43	22
44	3
45	2
46	510
47	285
48	70
49	39
50	22
51	3
52	1

n	a(n)
2	1
3	1
4	1
5	1
6	2
7	1
8	3
9	2
10	5
11	3
12	1
13	9
14	5
15	1
16	1
17	16
18	9
19	2
20	1
21	28
22	16
23	4
24	2
25	50
26	28
27	7
28	4
29	89
30	50
31	12
32	7
33	1
34	159
35	89
36	22
37	12
38	2
39	1
40	285
41	159
42	39
43	22
44	3
45	2
46	510
47	285
48	70
49	39
50	22
51	3
52	1