A103416 - cp's OEIS frontend

A103416 a(n) = n - ceiling(sqrt(prime(n))).

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

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

cp's OEIS Frontend

A103416 a(n) = n - ceiling(sqrt(prime(n))).

Table of values

List of values

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

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

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