A143942 - cp's OEIS frontend

A143942 Triangle read by rows: T(n,k) is the number of unordered pairs of vertices at distance k in a linear chain of n squares joined at vertices (i.e., joined like <><><>...<>; here <> is a square!); 1 <= k <= 2n.

n	a(n)
1	4
2	2
3	8
4	8
5	4
6	1
7	12
8	14
9	8
10	6
11	4
12	1
13	16
14	20
15	12
16	11
17	8
18	6
19	4
20	1
21	20
22	26
23	16
24	16
25	12
26	11
27	8
28	6
29	4
30	1
31	24
32	32
33	20
34	21
35	16
36	16
37	12
38	11
39	8
40	6
41	4
42	1
43	28
44	38
45	24
46	26
47	20
48	21
49	16
50	16
51	12
52	11
53	8
54	6
55	4
56	1
57	32
58	44
59	28
60	31
61	24
62	26
63	20
64	21
65	16
66	16
67	12
68	11
69	8
70	6
71	4
72	1
73	36
74	50
75	32
76	36
77	28
78	31
79	24
80	26

[4, 2, 8, 8, 4, 1, 12, 14, 8, 6, 4, 1, 16, 20, 12, 11, 8, 6, 4, 1, 20, 26, 16, 16, 12, 11, 8, 6, 4, 1, 24, 32, 20, 21, 16, 16, 12, 11, 8, 6, 4, 1, 28, 38, 24, 26, 20, 21, 16, 16, 12, 11, 8, 6, 4, 1, 32, 44, 28, 31, 24, 26, 20, 21, 16, 16, 12, 11, 8, 6, 4, 1, 36, 50, 32, 36, 28, 31, 24, 26]

cp's OEIS Frontend

A143942 Triangle read by rows: T(n,k) is the number of unordered pairs of vertices at distance k in a linear chain of n squares joined at vertices (i.e., joined like <><><>...<>; here <> is a square!); 1 <= k <= 2n.

Table of values

List of values

n	a(n)
1	4
2	2
3	8
4	8
5	4
6	1
7	12
8	14
9	8
10	6
11	4
12	1
13	16
14	20
15	12
16	11
17	8
18	6
19	4
20	1
21	20
22	26
23	16
24	16
25	12
26	11
27	8
28	6
29	4
30	1
31	24
32	32
33	20
34	21
35	16
36	16
37	12
38	11
39	8
40	6
41	4
42	1
43	28
44	38
45	24
46	26
47	20
48	21
49	16
50	16
51	12
52	11
53	8
54	6
55	4
56	1
57	32
58	44
59	28
60	31
61	24
62	26
63	20
64	21
65	16
66	16
67	12
68	11
69	8
70	6
71	4
72	1
73	36
74	50
75	32
76	36
77	28
78	31
79	24
80	26

n	a(n)
1	4
2	2
3	8
4	8
5	4
6	1
7	12
8	14
9	8
10	6
11	4
12	1
13	16
14	20
15	12
16	11
17	8
18	6
19	4
20	1
21	20
22	26
23	16
24	16
25	12
26	11
27	8
28	6
29	4
30	1
31	24
32	32
33	20
34	21
35	16
36	16
37	12
38	11
39	8
40	6
41	4
42	1
43	28
44	38
45	24
46	26
47	20
48	21
49	16
50	16
51	12
52	11
53	8
54	6
55	4
56	1
57	32
58	44
59	28
60	31
61	24
62	26
63	20
64	21
65	16
66	16
67	12
68	11
69	8
70	6
71	4
72	1
73	36
74	50
75	32
76	36
77	28
78	31
79	24
80	26

n	a(n)
1	4
2	2
3	8
4	8
5	4
6	1
7	12
8	14
9	8
10	6
11	4
12	1
13	16
14	20
15	12
16	11
17	8
18	6
19	4
20	1
21	20
22	26
23	16
24	16
25	12
26	11
27	8
28	6
29	4
30	1
31	24
32	32
33	20
34	21
35	16
36	16
37	12
38	11
39	8
40	6
41	4
42	1
43	28
44	38
45	24
46	26
47	20
48	21
49	16
50	16
51	12
52	11
53	8
54	6
55	4
56	1
57	32
58	44
59	28
60	31
61	24
62	26
63	20
64	21
65	16
66	16
67	12
68	11
69	8
70	6
71	4
72	1
73	36
74	50
75	32
76	36
77	28
78	31
79	24
80	26