A216625 - cp's OEIS frontend

A216625 Triangle read by rows, n >= 1, 1 <= k <= n, T(n,k) = Sum_{c|n,d|k} gcd(c,d).

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

[1, 2, 5, 2, 4, 6, 3, 8, 6, 15, 2, 4, 4, 6, 8, 4, 10, 12, 16, 8, 30, 2, 4, 4, 6, 4, 8, 10, 4, 11, 8, 22, 8, 22, 8, 37, 3, 6, 10, 9, 6, 20, 6, 12, 23, 4, 10, 8, 16, 16, 20, 8, 22, 12, 40, 2, 4, 4, 6, 4, 8, 4, 8, 6, 8, 14, 6, 16, 18, 30, 12, 48, 12, 44, 30, 32]

cp's OEIS Frontend

A216625 Triangle read by rows, n >= 1, 1 <= k <= n, T(n,k) = Sum_{c|n,d|k} gcd(c,d).

Table of values

List of values

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

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

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