A070817 - cp's OEIS frontend

A070817 a(n) = floor(n/2) - gpf(phi(n)), where gpf(n) is the largest prime factor of n.

n	a(n)
3	-1
4	0
5	0
6	1
7	0
8	2
9	1
10	3
11	0
12	4
13	3
14	4
15	5
16	6
17	6
18	6
19	6
20	8
21	7
22	6
23	0
24	10
25	7
26	10
27	10
28	11
29	7
30	13
31	10
32	14
33	11
34	15
35	14
36	15
37	15
38	16
39	16
40	18
41	15
42	18
43	14
44	17
45	19
46	12
47	0
48	22
49	17
50	20
51	23
52	23
53	13
54	24
55	22
56	25
57	25
58	22
59	0
60	28
61	25
62	26
63	28
64	30
65	29
66	28
67	22
68	32
69	23
70	32
71	28
72	33
73	33
74	34
75	32
76	35
77	33
78	36
79	26
80	38
81	37
82	36
83	0
84	39
85	40
86	36
87	36
88	39
89	33
90	42
91	42
92	35
93	41
94	24

[-1, 0, 0, 1, 0, 2, 1, 3, 0, 4, 3, 4, 5, 6, 6, 6, 6, 8, 7, 6, 0, 10, 7, 10, 10, 11, 7, 13, 10, 14, 11, 15, 14, 15, 15, 16, 16, 18, 15, 18, 14, 17, 19, 12, 0, 22, 17, 20, 23, 23, 13, 24, 22, 25, 25, 22, 0, 28, 25, 26, 28, 30, 29, 28, 22, 32, 23, 32, 28, 33, 33, 34, 32, 35, 33, 36, 26, 38, 37, 36, 0, 39, 40, 36, 36, 39, 33, 42, 42, 35, 41, 24]

cp's OEIS Frontend

A070817 a(n) = floor(n/2) - gpf(phi(n)), where gpf(n) is the largest prime factor of n.

Table of values

List of values

n	a(n)
3	-1
4	0
5	0
6	1
7	0
8	2
9	1
10	3
11	0
12	4
13	3
14	4
15	5
16	6
17	6
18	6
19	6
20	8
21	7
22	6
23	0
24	10
25	7
26	10
27	10
28	11
29	7
30	13
31	10
32	14
33	11
34	15
35	14
36	15
37	15
38	16
39	16
40	18
41	15
42	18
43	14
44	17
45	19
46	12
47	0
48	22
49	17
50	20
51	23
52	23
53	13
54	24
55	22
56	25
57	25
58	22
59	0
60	28
61	25
62	26
63	28
64	30
65	29
66	28
67	22
68	32
69	23
70	32
71	28
72	33
73	33
74	34
75	32
76	35
77	33
78	36
79	26
80	38
81	37
82	36
83	0
84	39
85	40
86	36
87	36
88	39
89	33
90	42
91	42
92	35
93	41
94	24

n	a(n)
3	-1
4	0
5	0
6	1
7	0
8	2
9	1
10	3
11	0
12	4
13	3
14	4
15	5
16	6
17	6
18	6
19	6
20	8
21	7
22	6
23	0
24	10
25	7
26	10
27	10
28	11
29	7
30	13
31	10
32	14
33	11
34	15
35	14
36	15
37	15
38	16
39	16
40	18
41	15
42	18
43	14
44	17
45	19
46	12
47	0
48	22
49	17
50	20
51	23
52	23
53	13
54	24
55	22
56	25
57	25
58	22
59	0
60	28
61	25
62	26
63	28
64	30
65	29
66	28
67	22
68	32
69	23
70	32
71	28
72	33
73	33
74	34
75	32
76	35
77	33
78	36
79	26
80	38
81	37
82	36
83	0
84	39
85	40
86	36
87	36
88	39
89	33
90	42
91	42
92	35
93	41
94	24

n	a(n)
3	-1
4	0
5	0
6	1
7	0
8	2
9	1
10	3
11	0
12	4
13	3
14	4
15	5
16	6
17	6
18	6
19	6
20	8
21	7
22	6
23	0
24	10
25	7
26	10
27	10
28	11
29	7
30	13
31	10
32	14
33	11
34	15
35	14
36	15
37	15
38	16
39	16
40	18
41	15
42	18
43	14
44	17
45	19
46	12
47	0
48	22
49	17
50	20
51	23
52	23
53	13
54	24
55	22
56	25
57	25
58	22
59	0
60	28
61	25
62	26
63	28
64	30
65	29
66	28
67	22
68	32
69	23
70	32
71	28
72	33
73	33
74	34
75	32
76	35
77	33
78	36
79	26
80	38
81	37
82	36
83	0
84	39
85	40
86	36
87	36
88	39
89	33
90	42
91	42
92	35
93	41
94	24