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.

A338639 a(0) = 1; for n > 0, a(n) = -Sum_{d|n, d < n} a(d - 1).

Table of values

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

List of values

[1, 0, -1, -1, -1, -1, 0, -1, 0, 0, 0, -1, 2, -1, -1, 1, 1, -1, 1, -1, 1, 0, -1, -1, 4, 0, -3, 0, 1, -1, 3, -1, 0, 0, -2, 0, 4, -1, -2, -2, 3, -1, 1, -1, 0, 2, 0, -1, 4, -1, -4, -1, -2, -1, 5, 0, 2, -1, -2, -1, 7, -1, -4, -1, 1, -2, 1, -1, -1, 1, 3, -1, 6, -1, -5, -2, 0, -1, 1, -1, 4]