A077088 - cp's OEIS frontend

A077088 a(n) = phi(sigma(n) - phi(n)), where phi is Euler's totient function and sigma is the sum of divisors function, with a(1) = 0.

n	a(n)
1	0
2	1
3	1
4	4
5	1
6	4
7	1
8	10
9	6
10	6
11	1
12	8
13	1
14	6
15	8
16	22
17	1
18	20
19	1
20	16
21	8
22	12
23	1
24	24
25	10
26	8
27	10
28	20
29	1
30	32
31	1
32	46
33	12
34	18
35	8
36	78
37	1
38	12
39	16
40	36
41	1
42	24
43	1
44	32
45	18
46	20
47	1
48	36
49	8
50	72
51	16
52	36
53	1
54	32
55	16
56	32
57	20
58	30
59	1
60	72
61	1
62	20
63	32
64	72
65	12
66	60
67	1
68	46
69	24
70	32
71	1
72	108
73	1
74	24
75	24
76	48
77	12
78	48
79	1
80	60

[0, 1, 1, 4, 1, 4, 1, 10, 6, 6, 1, 8, 1, 6, 8, 22, 1, 20, 1, 16, 8, 12, 1, 24, 10, 8, 10, 20, 1, 32, 1, 46, 12, 18, 8, 78, 1, 12, 16, 36, 1, 24, 1, 32, 18, 20, 1, 36, 8, 72, 16, 36, 1, 32, 16, 32, 20, 30, 1, 72, 1, 20, 32, 72, 12, 60, 1, 46, 24, 32, 1, 108, 1, 24, 24, 48, 12, 48, 1, 60]

cp's OEIS Frontend

A077088 a(n) = phi(sigma(n) - phi(n)), where phi is Euler's totient function and sigma is the sum of divisors function, with a(1) = 0.

Table of values

List of values

n	a(n)
1	0
2	1
3	1
4	4
5	1
6	4
7	1
8	10
9	6
10	6
11	1
12	8
13	1
14	6
15	8
16	22
17	1
18	20
19	1
20	16
21	8
22	12
23	1
24	24
25	10
26	8
27	10
28	20
29	1
30	32
31	1
32	46
33	12
34	18
35	8
36	78
37	1
38	12
39	16
40	36
41	1
42	24
43	1
44	32
45	18
46	20
47	1
48	36
49	8
50	72
51	16
52	36
53	1
54	32
55	16
56	32
57	20
58	30
59	1
60	72
61	1
62	20
63	32
64	72
65	12
66	60
67	1
68	46
69	24
70	32
71	1
72	108
73	1
74	24
75	24
76	48
77	12
78	48
79	1
80	60

n	a(n)
1	0
2	1
3	1
4	4
5	1
6	4
7	1
8	10
9	6
10	6
11	1
12	8
13	1
14	6
15	8
16	22
17	1
18	20
19	1
20	16
21	8
22	12
23	1
24	24
25	10
26	8
27	10
28	20
29	1
30	32
31	1
32	46
33	12
34	18
35	8
36	78
37	1
38	12
39	16
40	36
41	1
42	24
43	1
44	32
45	18
46	20
47	1
48	36
49	8
50	72
51	16
52	36
53	1
54	32
55	16
56	32
57	20
58	30
59	1
60	72
61	1
62	20
63	32
64	72
65	12
66	60
67	1
68	46
69	24
70	32
71	1
72	108
73	1
74	24
75	24
76	48
77	12
78	48
79	1
80	60

n	a(n)
1	0
2	1
3	1
4	4
5	1
6	4
7	1
8	10
9	6
10	6
11	1
12	8
13	1
14	6
15	8
16	22
17	1
18	20
19	1
20	16
21	8
22	12
23	1
24	24
25	10
26	8
27	10
28	20
29	1
30	32
31	1
32	46
33	12
34	18
35	8
36	78
37	1
38	12
39	16
40	36
41	1
42	24
43	1
44	32
45	18
46	20
47	1
48	36
49	8
50	72
51	16
52	36
53	1
54	32
55	16
56	32
57	20
58	30
59	1
60	72
61	1
62	20
63	32
64	72
65	12
66	60
67	1
68	46
69	24
70	32
71	1
72	108
73	1
74	24
75	24
76	48
77	12
78	48
79	1
80	60