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.

A341932 a(n) = largest k < n such that the decimal concatenation n||n-1||n-2||...||n-k is prime, or -1 if no such prime exists.

Table of values

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

List of values

[-1, -1, 0, 0, 1, 0, -1, 4, -1, -1, 3, 0, -1, 0, -1, -1, -1, 0, -1, 0, -1, -1, 3, 0, 1, 12, -1, 4, -1, 0, -1, 0, -1, -1, 1, -1, -1, 0, -1, -1, -1, 0, 1, 0, -1, -1, 43, 0, 31, -1, -1, 4, 15, 12, -1, 28, 9, -1, 1, 0, 13, 0, -1, -1, -1, -1, -1, 0, 57, -1, 1, 0, -1]