A286030 - cp's OEIS frontend

A286030 Irregular triangle T(n,k) read by rows: Let S be a 3-member set of integers {f,g,h} where f >= g >= h >= 0 and f+g+h = n. Let S(n,k) be an irregular triangle composed of all S listed in reverse lexicographic order by row n. Then T(n,k) = n!Q/(3f!g!h!), where Q is the number of permutations of S(n,k). (See "Comments" and "Examples" for additional explanation.)

n	a(n)
1	1
2	1
3	2
4	1
5	6
6	2
7	1
8	8
9	6
10	12
11	1
12	10
13	20
14	20
15	30
16	1
17	12
18	30
19	30
20	20
21	120
22	30
23	1
24	14
25	42
26	42
27	70
28	210
29	140
30	210
31	1
32	16
33	56
34	56
35	112
36	336
37	70
38	560
39	420
40	560
41	1
42	18
43	72
44	72
45	168
46	504
47	252
48	1008
49	756
50	630
51	2520
52	560

[1, 1, 2, 1, 6, 2, 1, 8, 6, 12, 1, 10, 20, 20, 30, 1, 12, 30, 30, 20, 120, 30, 1, 14, 42, 42, 70, 210, 140, 210, 1, 16, 56, 56, 112, 336, 70, 560, 420, 560, 1, 18, 72, 72, 168, 504, 252, 1008, 756, 630, 2520, 560]

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