cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A024919 a(n) = Sum_{k=1..n} (-1)^k*k*floor(n/k).

Table of values

n a(n)
1 -1
2 0
3 -4
4 1
5 -5
6 -1
7 -9
8 4
9 -9
10 -3
11 -15
12 5
13 -9
14 -1
15 -25
16 4
17 -14
18 -1
19 -21
20 9
21 -23
22 -11
23 -35
24 17
25 -14
26 0
27 -40
28 0
29 -30
30 -6
31 -38
32 23
33 -25
34 -7
35 -55
36 10
37 -28
38 -8
39 -64
40 14
41 -28
42 4
43 -40
44 20
45 -58
46 -34
47 -82
48 34
49 -23
50 8
51 -64
52 6
53 -48
54 -8
55 -80
56 24
57 -56
58 -26
59 -86
60 34
61 -28
62 4
63 -100
64 25
65 -59

List of values

[-1, 0, -4, 1, -5, -1, -9, 4, -9, -3, -15, 5, -9, -1, -25, 4, -14, -1, -21, 9, -23, -11, -35, 17, -14, 0, -40, 0, -30, -6, -38, 23, -25, -7, -55, 10, -28, -8, -64, 14, -28, 4, -40, 20, -58, -34, -82, 34, -23, 8, -64, 6, -48, -8, -80, 24, -56, -26, -86, 34, -28, 4, -100, 25, -59]