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 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 17 |
| 4 | 84 |
| 5 | 485 |
| 6 | 3236 |
| 7 | 24609 |
| 8 | 210572 |
| 9 | 2004749 |
| 10 | 21033900 |
| 11 | 241237001 |
| 12 | 3003349124 |
| 13 | 40345599957 |
| 14 | 581765196884 |
| 15 | 8963453118065 |
| 16 | 146969877361116 |
| 17 | 2555361954692189 |
| 18 | 46963373856864092 |
| 19 | 909707559383702169 |
| 20 | 18524816853636447380 |
| 21 | 395634467245613474981 |