A216620 - cp's OEIS frontend

A216620 Square array read by antidiagonals: T(n,k) = Sum_{c|n,d|k} phi(gcd(c,d)) for n>=1, k>=1.

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

[1, 2, 2, 2, 4, 2, 3, 4, 4, 3, 2, 6, 5, 6, 2, 4, 4, 6, 6, 4, 4, 2, 8, 4, 10, 4, 8, 2, 4, 4, 10, 6, 6, 10, 4, 4, 3, 8, 4, 12, 7, 12, 4, 8, 3, 4, 6, 8, 6, 8, 8, 6, 8, 6, 4, 2, 8, 8, 14, 4, 20, 4, 14, 8, 8, 2, 6, 4, 8, 9, 8, 8, 8, 8, 9, 8, 4, 6, 2, 12, 4, 12, 6]

cp's OEIS Frontend

A216620 Square array read by antidiagonals: T(n,k) = Sum_{c|n,d|k} phi(gcd(c,d)) for n>=1, k>=1.

Table of values

List of values

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

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

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