A143940 - cp's OEIS frontend

A143940 Triangle read by rows: T(n,k) is the number of unordered pairs of vertices at distance k in a linear chain of n triangles (i.e., joined like VVV..VV; here V is a triangle!), 1 <= k <= n.

n	a(n)
1	3
2	6
3	4
4	9
5	8
6	4
7	12
8	12
9	8
10	4
11	15
12	16
13	12
14	8
15	4
16	18
17	20
18	16
19	12
20	8
21	4
22	21
23	24
24	20
25	16
26	12
27	8
28	4
29	24
30	28
31	24
32	20
33	16
34	12
35	8
36	4
37	27
38	32
39	28
40	24
41	20
42	16
43	12
44	8
45	4
46	30
47	36
48	32
49	28
50	24
51	20
52	16
53	12
54	8
55	4
56	33
57	40
58	36
59	32
60	28
61	24
62	20
63	16
64	12
65	8
66	4
67	36
68	44
69	40
70	36
71	32
72	28
73	24
74	20
75	16
76	12
77	8
78	4

[3, 6, 4, 9, 8, 4, 12, 12, 8, 4, 15, 16, 12, 8, 4, 18, 20, 16, 12, 8, 4, 21, 24, 20, 16, 12, 8, 4, 24, 28, 24, 20, 16, 12, 8, 4, 27, 32, 28, 24, 20, 16, 12, 8, 4, 30, 36, 32, 28, 24, 20, 16, 12, 8, 4, 33, 40, 36, 32, 28, 24, 20, 16, 12, 8, 4, 36, 44, 40, 36, 32, 28, 24, 20, 16, 12, 8, 4]

cp's OEIS Frontend

A143940 Triangle read by rows: T(n,k) is the number of unordered pairs of vertices at distance k in a linear chain of n triangles (i.e., joined like VVV..VV; here V is a triangle!), 1 <= k <= n.

Table of values

List of values

n	a(n)
1	3
2	6
3	4
4	9
5	8
6	4
7	12
8	12
9	8
10	4
11	15
12	16
13	12
14	8
15	4
16	18
17	20
18	16
19	12
20	8
21	4
22	21
23	24
24	20
25	16
26	12
27	8
28	4
29	24
30	28
31	24
32	20
33	16
34	12
35	8
36	4
37	27
38	32
39	28
40	24
41	20
42	16
43	12
44	8
45	4
46	30
47	36
48	32
49	28
50	24
51	20
52	16
53	12
54	8
55	4
56	33
57	40
58	36
59	32
60	28
61	24
62	20
63	16
64	12
65	8
66	4
67	36
68	44
69	40
70	36
71	32
72	28
73	24
74	20
75	16
76	12
77	8
78	4

n	a(n)
1	3
2	6
3	4
4	9
5	8
6	4
7	12
8	12
9	8
10	4
11	15
12	16
13	12
14	8
15	4
16	18
17	20
18	16
19	12
20	8
21	4
22	21
23	24
24	20
25	16
26	12
27	8
28	4
29	24
30	28
31	24
32	20
33	16
34	12
35	8
36	4
37	27
38	32
39	28
40	24
41	20
42	16
43	12
44	8
45	4
46	30
47	36
48	32
49	28
50	24
51	20
52	16
53	12
54	8
55	4
56	33
57	40
58	36
59	32
60	28
61	24
62	20
63	16
64	12
65	8
66	4
67	36
68	44
69	40
70	36
71	32
72	28
73	24
74	20
75	16
76	12
77	8
78	4

n	a(n)
1	3
2	6
3	4
4	9
5	8
6	4
7	12
8	12
9	8
10	4
11	15
12	16
13	12
14	8
15	4
16	18
17	20
18	16
19	12
20	8
21	4
22	21
23	24
24	20
25	16
26	12
27	8
28	4
29	24
30	28
31	24
32	20
33	16
34	12
35	8
36	4
37	27
38	32
39	28
40	24
41	20
42	16
43	12
44	8
45	4
46	30
47	36
48	32
49	28
50	24
51	20
52	16
53	12
54	8
55	4
56	33
57	40
58	36
59	32
60	28
61	24
62	20
63	16
64	12
65	8
66	4
67	36
68	44
69	40
70	36
71	32
72	28
73	24
74	20
75	16
76	12
77	8
78	4