A333505 - cp's OEIS frontend

A333505 a(n) = Sum_{k=1..n} (-1)^(k+1) * k * ceiling(n/k).

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

[1, 0, 2, 2, 2, 2, 5, 5, 1, 4, 9, 9, 2, 2, 9, 17, 5, 5, 11, 11, 2, 12, 23, 23, -4, 1, 14, 26, 15, 15, 22, 22, -6, 8, 25, 37, 9, 9, 28, 44, 7, 7, 18, 18, 3, 35, 58, 58, -9, -2, 18, 38, 21, 21, 36, 52, 5, 27, 56, 56, -3, -3, 28, 68, 8, 26, 45, 45, 24, 50, 73, 73, -23, -23, 14]

cp's OEIS Frontend

A333505 a(n) = Sum_{k=1..n} (-1)^(k+1) * k * ceiling(n/k).

Table of values

List of values

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

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

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