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 | 1 |
| 5 | 6 |
| 6 | 54 |
| 7 | 416 |
| 8 | 3111 |
| 9 | 22898 |
| 10 | 168460 |
| 11 | 1242985 |
| 12 | 9227333 |
| 13 | 68949103 |
| 14 | 518618196 |
| 15 | 3925228596 |
| 16 | 29879207817 |
| 17 | 228630283775 |
| 18 | 1757699977107 |
| 19 | 13570824097968 |
| 20 | 105182547181534 |
| 21 | 818093724437992 |
| 22 | 6383353614308209 |