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) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 18 |
| 5 | 86 |
| 6 | 500 |
| 7 | 3423 |
| 8 | 26889 |
| 9 | 238158 |
| 10 | 2347554 |
| 11 | 25487721 |
| 12 | 302211543 |
| 13 | 3885576979 |
| 14 | 53842995268 |
| 15 | 799953072549 |
| 16 | 12684970150411 |
| 17 | 213832353964067 |
| 18 | 3818434892215474 |
| 19 | 72004772253206073 |
| 20 | 1429809049027949160 |