A330823 - cp's OEIS frontend

A330823 a(1) = 1; for n > 1, a(n) = a(n-1) - n if n is prime, otherwise a(n) = a(n-1) + floor(n/(log(n)-1)).

n	a(n)
1	1
2	-1
3	-4
4	6
5	1
6	8
7	1
8	8
9	15
10	22
11	11
12	19
13	6
14	14
15	22
16	31
17	14
18	23
19	4
20	14
21	24
22	34
23	11
24	22
25	33
26	44
27	55
28	67
29	38
30	50
31	19
32	31
33	44
34	57
35	70
36	83
37	46
38	60
39	74
40	88
41	47
42	62
43	19
44	34
45	50
46	66
47	19
48	35
49	51
50	68
51	85
52	102
53	49
54	67
55	85
56	103
57	121
58	139
59	80
60	99
61	38
62	57
63	77
64	97
65	117
66	137
67	70

[1, -1, -4, 6, 1, 8, 1, 8, 15, 22, 11, 19, 6, 14, 22, 31, 14, 23, 4, 14, 24, 34, 11, 22, 33, 44, 55, 67, 38, 50, 19, 31, 44, 57, 70, 83, 46, 60, 74, 88, 47, 62, 19, 34, 50, 66, 19, 35, 51, 68, 85, 102, 49, 67, 85, 103, 121, 139, 80, 99, 38, 57, 77, 97, 117, 137, 70]

cp's OEIS Frontend

A330823 a(1) = 1; for n > 1, a(n) = a(n-1) - n if n is prime, otherwise a(n) = a(n-1) + floor(n/(log(n)-1)).

Table of values

List of values

n	a(n)
1	1
2	-1
3	-4
4	6
5	1
6	8
7	1
8	8
9	15
10	22
11	11
12	19
13	6
14	14
15	22
16	31
17	14
18	23
19	4
20	14
21	24
22	34
23	11
24	22
25	33
26	44
27	55
28	67
29	38
30	50
31	19
32	31
33	44
34	57
35	70
36	83
37	46
38	60
39	74
40	88
41	47
42	62
43	19
44	34
45	50
46	66
47	19
48	35
49	51
50	68
51	85
52	102
53	49
54	67
55	85
56	103
57	121
58	139
59	80
60	99
61	38
62	57
63	77
64	97
65	117
66	137
67	70

n	a(n)
1	1
2	-1
3	-4
4	6
5	1
6	8
7	1
8	8
9	15
10	22
11	11
12	19
13	6
14	14
15	22
16	31
17	14
18	23
19	4
20	14
21	24
22	34
23	11
24	22
25	33
26	44
27	55
28	67
29	38
30	50
31	19
32	31
33	44
34	57
35	70
36	83
37	46
38	60
39	74
40	88
41	47
42	62
43	19
44	34
45	50
46	66
47	19
48	35
49	51
50	68
51	85
52	102
53	49
54	67
55	85
56	103
57	121
58	139
59	80
60	99
61	38
62	57
63	77
64	97
65	117
66	137
67	70

n	a(n)
1	1
2	-1
3	-4
4	6
5	1
6	8
7	1
8	8
9	15
10	22
11	11
12	19
13	6
14	14
15	22
16	31
17	14
18	23
19	4
20	14
21	24
22	34
23	11
24	22
25	33
26	44
27	55
28	67
29	38
30	50
31	19
32	31
33	44
34	57
35	70
36	83
37	46
38	60
39	74
40	88
41	47
42	62
43	19
44	34
45	50
46	66
47	19
48	35
49	51
50	68
51	85
52	102
53	49
54	67
55	85
56	103
57	121
58	139
59	80
60	99
61	38
62	57
63	77
64	97
65	117
66	137
67	70