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.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 4 |
| 6 | 63 |
| 7 | 665 |
| 8 | 5982 |
| 9 | 49748 |
| 10 | 396642 |
| 11 | 3089010 |
| 12 | 23745117 |
| 13 | 181282899 |
| 14 | 1379847138 |
| 15 | 10496697584 |
| 16 | 79928658289 |
| 17 | 609847716251 |
| 18 | 4665446254886 |
| 19 | 35801131210504 |
| 20 | 275638351332190 |
| 21 | 2129514056354378 |
| 22 | 16509890253429971 |
| 23 | 128449405928666831 |
| 24 | 1002835093225654416 |
| 25 | 7856166360951643384 |