A071860 - cp's OEIS frontend

A071860 Number of k 1<=k<=n such that sigma(k) is odd.

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

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

cp's OEIS Frontend

A071860 Number of k 1<=k<=n such that sigma(k) is odd.

Table of values

List of values

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

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

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