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.

A372626 a(1) = 1; a(n) = Sum_{d|n, d <= sqrt(n)} (-1)^(n/d + 1) * a(d).

Table of values

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

List of values

[1, -1, 1, 0, 1, -2, 1, 0, 2, -2, 1, -1, 1, -2, 2, 0, 1, -3, 1, 0, 2, -2, 1, -1, 2, -2, 2, 0, 1, -4, 1, 0, 2, -2, 2, 1, 1, -2, 2, -1, 1, -5, 1, 0, 3, -2, 1, 1, 2, -3, 2, 0, 1, -5, 2, -1, 2, -2, 1, 0, 1, -2, 3, 0, 2, -5, 1, 0, 2, -4, 1, 1, 1, -2, 3, 0, 2, -5, 1, -1]