A338993 - cp's OEIS frontend

A338993 Triangle read by rows: T(n,k) is the number of k-permutations of {1,...,n} that form a nontrivial arithmetic progression, 1 <= k <= n.

n	a(n)
1	1
2	2
3	2
4	3
5	6
6	2
7	4
8	12
9	4
10	2
11	5
12	20
13	8
14	4
15	2
16	6
17	30
18	12
19	6
20	4
21	2
22	7
23	42
24	18
25	10
26	6
27	4
28	2
29	8
30	56
31	24
32	14
33	8
34	6
35	4
36	2
37	9
38	72
39	32
40	18
41	12
42	8
43	6
44	4
45	2
46	10
47	90
48	40
49	24
50	16
51	10
52	8
53	6
54	4
55	2
56	11
57	110
58	50
59	30
60	20
61	14
62	10
63	8
64	6
65	4
66	2
67	12
68	132
69	60
70	36
71	24
72	18
73	12
74	10
75	8
76	6
77	4
78	2

[1, 2, 2, 3, 6, 2, 4, 12, 4, 2, 5, 20, 8, 4, 2, 6, 30, 12, 6, 4, 2, 7, 42, 18, 10, 6, 4, 2, 8, 56, 24, 14, 8, 6, 4, 2, 9, 72, 32, 18, 12, 8, 6, 4, 2, 10, 90, 40, 24, 16, 10, 8, 6, 4, 2, 11, 110, 50, 30, 20, 14, 10, 8, 6, 4, 2, 12, 132, 60, 36, 24, 18, 12, 10, 8, 6, 4, 2]

cp's OEIS Frontend

A338993 Triangle read by rows: T(n,k) is the number of k-permutations of {1,...,n} that form a nontrivial arithmetic progression, 1 <= k <= n.

Table of values

List of values

n	a(n)
1	1
2	2
3	2
4	3
5	6
6	2
7	4
8	12
9	4
10	2
11	5
12	20
13	8
14	4
15	2
16	6
17	30
18	12
19	6
20	4
21	2
22	7
23	42
24	18
25	10
26	6
27	4
28	2
29	8
30	56
31	24
32	14
33	8
34	6
35	4
36	2
37	9
38	72
39	32
40	18
41	12
42	8
43	6
44	4
45	2
46	10
47	90
48	40
49	24
50	16
51	10
52	8
53	6
54	4
55	2
56	11
57	110
58	50
59	30
60	20
61	14
62	10
63	8
64	6
65	4
66	2
67	12
68	132
69	60
70	36
71	24
72	18
73	12
74	10
75	8
76	6
77	4
78	2

n	a(n)
1	1
2	2
3	2
4	3
5	6
6	2
7	4
8	12
9	4
10	2
11	5
12	20
13	8
14	4
15	2
16	6
17	30
18	12
19	6
20	4
21	2
22	7
23	42
24	18
25	10
26	6
27	4
28	2
29	8
30	56
31	24
32	14
33	8
34	6
35	4
36	2
37	9
38	72
39	32
40	18
41	12
42	8
43	6
44	4
45	2
46	10
47	90
48	40
49	24
50	16
51	10
52	8
53	6
54	4
55	2
56	11
57	110
58	50
59	30
60	20
61	14
62	10
63	8
64	6
65	4
66	2
67	12
68	132
69	60
70	36
71	24
72	18
73	12
74	10
75	8
76	6
77	4
78	2

n	a(n)
1	1
2	2
3	2
4	3
5	6
6	2
7	4
8	12
9	4
10	2
11	5
12	20
13	8
14	4
15	2
16	6
17	30
18	12
19	6
20	4
21	2
22	7
23	42
24	18
25	10
26	6
27	4
28	2
29	8
30	56
31	24
32	14
33	8
34	6
35	4
36	2
37	9
38	72
39	32
40	18
41	12
42	8
43	6
44	4
45	2
46	10
47	90
48	40
49	24
50	16
51	10
52	8
53	6
54	4
55	2
56	11
57	110
58	50
59	30
60	20
61	14
62	10
63	8
64	6
65	4
66	2
67	12
68	132
69	60
70	36
71	24
72	18
73	12
74	10
75	8
76	6
77	4
78	2