A004221 - cp's OEIS frontend

A004221 a(n) = ceiling(10*log_10(n)).

n	a(n)
1	0
2	4
3	5
4	7
5	7
6	8
7	9
8	10
9	10
10	10
11	11
12	11
13	12
14	12
15	12
16	13
17	13
18	13
19	13
20	14
21	14
22	14
23	14
24	14
25	14
26	15
27	15
28	15
29	15
30	15
31	15
32	16
33	16
34	16
35	16
36	16
37	16
38	16
39	16
40	17
41	17
42	17
43	17
44	17
45	17
46	17
47	17
48	17
49	17
50	17
51	18
52	18
53	18
54	18
55	18
56	18
57	18

[0, 4, 5, 7, 7, 8, 9, 10, 10, 10, 11, 11, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18]

cp's OEIS Frontend

A004221 a(n) = ceiling(10*log_10(n)).

Table of values

List of values

n	a(n)
1	0
2	4
3	5
4	7
5	7
6	8
7	9
8	10
9	10
10	10
11	11
12	11
13	12
14	12
15	12
16	13
17	13
18	13
19	13
20	14
21	14
22	14
23	14
24	14
25	14
26	15
27	15
28	15
29	15
30	15
31	15
32	16
33	16
34	16
35	16
36	16
37	16
38	16
39	16
40	17
41	17
42	17
43	17
44	17
45	17
46	17
47	17
48	17
49	17
50	17
51	18
52	18
53	18
54	18
55	18
56	18
57	18

n	a(n)
1	0
2	4
3	5
4	7
5	7
6	8
7	9
8	10
9	10
10	10
11	11
12	11
13	12
14	12
15	12
16	13
17	13
18	13
19	13
20	14
21	14
22	14
23	14
24	14
25	14
26	15
27	15
28	15
29	15
30	15
31	15
32	16
33	16
34	16
35	16
36	16
37	16
38	16
39	16
40	17
41	17
42	17
43	17
44	17
45	17
46	17
47	17
48	17
49	17
50	17
51	18
52	18
53	18
54	18
55	18
56	18
57	18

n	a(n)
1	0
2	4
3	5
4	7
5	7
6	8
7	9
8	10
9	10
10	10
11	11
12	11
13	12
14	12
15	12
16	13
17	13
18	13
19	13
20	14
21	14
22	14
23	14
24	14
25	14
26	15
27	15
28	15
29	15
30	15
31	15
32	16
33	16
34	16
35	16
36	16
37	16
38	16
39	16
40	17
41	17
42	17
43	17
44	17
45	17
46	17
47	17
48	17
49	17
50	17
51	18
52	18
53	18
54	18
55	18
56	18
57	18