A010554 - cp's OEIS frontend

A010554 a(n) = phi(phi(n)), where phi is the Euler totient function.

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

[1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 4, 2, 4, 2, 4, 4, 8, 2, 6, 4, 4, 4, 10, 4, 8, 4, 6, 4, 12, 4, 8, 8, 8, 8, 8, 4, 12, 6, 8, 8, 16, 4, 12, 8, 8, 10, 22, 8, 12, 8, 16, 8, 24, 6, 16, 8, 12, 12, 28, 8, 16, 8, 12, 16, 16, 8, 20, 16, 20, 8, 24, 8]

cp's OEIS Frontend

A010554 a(n) = phi(phi(n)), where phi is the Euler totient function.

Table of values

List of values

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

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

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