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.

A288571 a(n) = Sum_{d|n} (-1)^(n/d+1)*tau(d), where tau = number of divisors (A000005).

Table of values

n a(n)
1 1
2 1
3 3
4 0
5 3
6 3
7 3
8 -2
9 6
10 3
11 3
12 0
13 3
14 3
15 9
16 -5
17 3
18 6
19 3
20 0
21 9
22 3
23 3
24 -6
25 6
26 3
27 10
28 0
29 3
30 9
31 3
32 -9
33 9
34 3
35 9
36 0
37 3
38 3
39 9
40 -6
41 3
42 9
43 3
44 0
45 18
46 3
47 3
48 -15
49 6
50 6
51 9
52 0
53 3
54 10
55 9
56 -6
57 9
58 3
59 3
60 0
61 3
62 3
63 18
64 -14
65 9
66 9
67 3
68 0
69 9
70 9
71 3
72 -12
73 3
74 3
75 18
76 0
77 9
78 9
79 3
80 -15
81 15
82 3
83 3
84 0
85 9

List of values

[1, 1, 3, 0, 3, 3, 3, -2, 6, 3, 3, 0, 3, 3, 9, -5, 3, 6, 3, 0, 9, 3, 3, -6, 6, 3, 10, 0, 3, 9, 3, -9, 9, 3, 9, 0, 3, 3, 9, -6, 3, 9, 3, 0, 18, 3, 3, -15, 6, 6, 9, 0, 3, 10, 9, -6, 9, 3, 3, 0, 3, 3, 18, -14, 9, 9, 3, 0, 9, 9, 3, -12, 3, 3, 18, 0, 9, 9, 3, -15, 15, 3, 3, 0, 9]