A154585 - cp's OEIS frontend

A154585 a(n) = abs(Sum_{k=1..n} (-1)^k * (n-k+1 mod k)).

n	a(n)
1	0
2	1
3	1
4	0
5	1
6	2
7	4
8	0
9	3
10	4
11	5
12	4
13	1
14	10
15	4
16	3
17	1
18	2
19	9
20	2
21	11
22	12
23	17
24	11
25	0
26	13
27	0
28	1
29	6
30	7
31	23
32	8
33	7
34	20
35	10
36	9
37	8
38	25
39	14
40	13
41	4
42	3
43	20
44	13
45	34
46	35
47	34
48	26
49	8
50	13
51	6
52	5
53	8
54	25
55	24
56	1
57	26
58	27
59	34
60	33
61	4
62	37
63	25
64	6
65	11
66	12
67	11
68	16
69	37
70	38
71	60
72	59
73	24
74	25
75	0
76	19
77	40
78	41
79	54
80	14
81	25
82	26
83	51

[0, 1, 1, 0, 1, 2, 4, 0, 3, 4, 5, 4, 1, 10, 4, 3, 1, 2, 9, 2, 11, 12, 17, 11, 0, 13, 0, 1, 6, 7, 23, 8, 7, 20, 10, 9, 8, 25, 14, 13, 4, 3, 20, 13, 34, 35, 34, 26, 8, 13, 6, 5, 8, 25, 24, 1, 26, 27, 34, 33, 4, 37, 25, 6, 11, 12, 11, 16, 37, 38, 60, 59, 24, 25, 0, 19, 40, 41, 54, 14, 25, 26, 51]

cp's OEIS Frontend

A154585 a(n) = abs(Sum_{k=1..n} (-1)^k * (n-k+1 mod k)).

Table of values

List of values

n	a(n)
1	0
2	1
3	1
4	0
5	1
6	2
7	4
8	0
9	3
10	4
11	5
12	4
13	1
14	10
15	4
16	3
17	1
18	2
19	9
20	2
21	11
22	12
23	17
24	11
25	0
26	13
27	0
28	1
29	6
30	7
31	23
32	8
33	7
34	20
35	10
36	9
37	8
38	25
39	14
40	13
41	4
42	3
43	20
44	13
45	34
46	35
47	34
48	26
49	8
50	13
51	6
52	5
53	8
54	25
55	24
56	1
57	26
58	27
59	34
60	33
61	4
62	37
63	25
64	6
65	11
66	12
67	11
68	16
69	37
70	38
71	60
72	59
73	24
74	25
75	0
76	19
77	40
78	41
79	54
80	14
81	25
82	26
83	51

n	a(n)
1	0
2	1
3	1
4	0
5	1
6	2
7	4
8	0
9	3
10	4
11	5
12	4
13	1
14	10
15	4
16	3
17	1
18	2
19	9
20	2
21	11
22	12
23	17
24	11
25	0
26	13
27	0
28	1
29	6
30	7
31	23
32	8
33	7
34	20
35	10
36	9
37	8
38	25
39	14
40	13
41	4
42	3
43	20
44	13
45	34
46	35
47	34
48	26
49	8
50	13
51	6
52	5
53	8
54	25
55	24
56	1
57	26
58	27
59	34
60	33
61	4
62	37
63	25
64	6
65	11
66	12
67	11
68	16
69	37
70	38
71	60
72	59
73	24
74	25
75	0
76	19
77	40
78	41
79	54
80	14
81	25
82	26
83	51

n	a(n)
1	0
2	1
3	1
4	0
5	1
6	2
7	4
8	0
9	3
10	4
11	5
12	4
13	1
14	10
15	4
16	3
17	1
18	2
19	9
20	2
21	11
22	12
23	17
24	11
25	0
26	13
27	0
28	1
29	6
30	7
31	23
32	8
33	7
34	20
35	10
36	9
37	8
38	25
39	14
40	13
41	4
42	3
43	20
44	13
45	34
46	35
47	34
48	26
49	8
50	13
51	6
52	5
53	8
54	25
55	24
56	1
57	26
58	27
59	34
60	33
61	4
62	37
63	25
64	6
65	11
66	12
67	11
68	16
69	37
70	38
71	60
72	59
73	24
74	25
75	0
76	19
77	40
78	41
79	54
80	14
81	25
82	26
83	51