A072688 - cp's OEIS frontend

A072688 Of the first n integers (inclusive), how many of them have a prime number of letters in their English names?

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

[1, 2, 3, 3, 3, 4, 5, 6, 6, 7, 7, 7, 7, 7, 8, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 11, 12, 12, 12, 12, 12, 13, 13, 13, 13, 14, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 18, 18, 19, 19]

cp's OEIS Frontend

A072688 Of the first n integers (inclusive), how many of them have a prime number of letters in their English names?

Table of values

List of values

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

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

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