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.

A369886 a(n) is the least positive integer that can be expressed as +- 1 +- 2 +- 3 +- ... +- n in exactly n ways, or -1 if no such integer exists.

Table of values

n a(n)
1 1
2 -1
3 -1
4 -1
5 -1
6 -1
7 6
8 16
9 25
10 35
11 -1
12 56
13 -1
14 -1
15 96
16 -1
17 -1
18 145
19 -1
20 -1
21 -1
22 225
23 -1
24 -1
25 -1
26 -1
27 348
28 -1
29 -1
30 -1
31 -1
32 496
33 -1
34 -1
35 -1
36 -1
37 -1
38 707
39 -1
40 -1
41 -1
42 -1
43 -1
44 -1
45 -1
46 1045
47 -1
48 -1
49 -1
50 -1
51 -1
52 -1
53 -1
54 1447
55 -1

List of values

[1, -1, -1, -1, -1, -1, 6, 16, 25, 35, -1, 56, -1, -1, 96, -1, -1, 145, -1, -1, -1, 225, -1, -1, -1, -1, 348, -1, -1, -1, -1, 496, -1, -1, -1, -1, -1, 707, -1, -1, -1, -1, -1, -1, -1, 1045, -1, -1, -1, -1, -1, -1, -1, 1447, -1]