A081520 - cp's OEIS frontend

A081520 Triangle read by rows in which row n consists of 1 and the n-1 smallest positive numbers having common factors with n.

n	a(n)
1	1
2	1
3	2
4	1
5	3
6	6
7	1
8	2
9	4
10	6
11	1
12	5
13	10
14	15
15	20
16	1
17	2
18	3
19	4
20	6
21	8
22	1
23	7
24	14
25	21
26	28
27	35
28	42
29	1
30	2
31	4
32	6
33	8
34	10
35	12
36	14
37	1
38	3
39	6
40	9
41	12
42	15
43	18
44	21
45	24
46	1
47	2
48	4
49	5
50	6
51	8
52	10
53	12
54	14
55	15
56	1
57	11
58	22
59	33
60	44
61	55
62	66
63	77
64	88
65	99
66	110
67	1
68	2
69	3
70	4
71	6
72	8
73	9
74	10
75	12
76	14
77	15
78	16
79	1
80	13
81	26
82	39
83	52
84	65
85	78

[1, 1, 2, 1, 3, 6, 1, 2, 4, 6, 1, 5, 10, 15, 20, 1, 2, 3, 4, 6, 8, 1, 7, 14, 21, 28, 35, 42, 1, 2, 4, 6, 8, 10, 12, 14, 1, 3, 6, 9, 12, 15, 18, 21, 24, 1, 2, 4, 5, 6, 8, 10, 12, 14, 15, 1, 11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 1, 2, 3, 4, 6, 8, 9, 10, 12, 14, 15, 16, 1, 13, 26, 39, 52, 65, 78]

cp's OEIS Frontend

A081520 Triangle read by rows in which row n consists of 1 and the n-1 smallest positive numbers having common factors with n.

Table of values

List of values

n	a(n)
1	1
2	1
3	2
4	1
5	3
6	6
7	1
8	2
9	4
10	6
11	1
12	5
13	10
14	15
15	20
16	1
17	2
18	3
19	4
20	6
21	8
22	1
23	7
24	14
25	21
26	28
27	35
28	42
29	1
30	2
31	4
32	6
33	8
34	10
35	12
36	14
37	1
38	3
39	6
40	9
41	12
42	15
43	18
44	21
45	24
46	1
47	2
48	4
49	5
50	6
51	8
52	10
53	12
54	14
55	15
56	1
57	11
58	22
59	33
60	44
61	55
62	66
63	77
64	88
65	99
66	110
67	1
68	2
69	3
70	4
71	6
72	8
73	9
74	10
75	12
76	14
77	15
78	16
79	1
80	13
81	26
82	39
83	52
84	65
85	78

n	a(n)
1	1
2	1
3	2
4	1
5	3
6	6
7	1
8	2
9	4
10	6
11	1
12	5
13	10
14	15
15	20
16	1
17	2
18	3
19	4
20	6
21	8
22	1
23	7
24	14
25	21
26	28
27	35
28	42
29	1
30	2
31	4
32	6
33	8
34	10
35	12
36	14
37	1
38	3
39	6
40	9
41	12
42	15
43	18
44	21
45	24
46	1
47	2
48	4
49	5
50	6
51	8
52	10
53	12
54	14
55	15
56	1
57	11
58	22
59	33
60	44
61	55
62	66
63	77
64	88
65	99
66	110
67	1
68	2
69	3
70	4
71	6
72	8
73	9
74	10
75	12
76	14
77	15
78	16
79	1
80	13
81	26
82	39
83	52
84	65
85	78

n	a(n)
1	1
2	1
3	2
4	1
5	3
6	6
7	1
8	2
9	4
10	6
11	1
12	5
13	10
14	15
15	20
16	1
17	2
18	3
19	4
20	6
21	8
22	1
23	7
24	14
25	21
26	28
27	35
28	42
29	1
30	2
31	4
32	6
33	8
34	10
35	12
36	14
37	1
38	3
39	6
40	9
41	12
42	15
43	18
44	21
45	24
46	1
47	2
48	4
49	5
50	6
51	8
52	10
53	12
54	14
55	15
56	1
57	11
58	22
59	33
60	44
61	55
62	66
63	77
64	88
65	99
66	110
67	1
68	2
69	3
70	4
71	6
72	8
73	9
74	10
75	12
76	14
77	15
78	16
79	1
80	13
81	26
82	39
83	52
84	65
85	78