A071825 - cp's OEIS frontend

A071825 a(n) = (number of x with largest prime factor of the form 4k+3 less than or equal to n) minus (number of x with largest prime factor of the form 4k+1 less than or equal to n).

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

[0, 0, 1, 1, 0, 1, 2, 2, 3, 2, 3, 4, 3, 4, 3, 3, 2, 3, 4, 3, 4, 5, 6, 7, 6, 5, 6, 7, 6, 5, 6, 6, 7, 6, 7, 8, 7, 8, 7, 6, 5, 6, 7, 8, 7, 8, 9, 10, 11, 10, 9, 8, 7, 8, 9, 10, 11, 10, 11, 10, 9, 10, 11, 11, 10, 11, 12, 11, 12, 13, 14, 15, 14, 13, 12, 13, 14, 13, 14, 13, 14, 13, 14, 15, 14, 15, 14, 15]

cp's OEIS Frontend

A071825 a(n) = (number of x with largest prime factor of the form 4k+3 less than or equal to n) minus (number of x with largest prime factor of the form 4k+1 less than or equal to n).

Table of values

List of values

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

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

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