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 | 3 |
| 4 | 20 |
| 5 | 100 |
| 6 | 612 |
| 7 | 4389 |
| 8 | 35688 |
| 9 | 325395 |
| 10 | 3288490 |
| 11 | 36489992 |
| 12 | 441093864 |
| 13 | 5770007009 |
| 14 | 81213878830 |
| 15 | 1223895060315 |
| 16 | 19662509071056 |
| 17 | 335472890422812 |
| 18 | 6057979285535388 |
| 19 | 115434096553014565 |
| 20 | 2314691409652237700 |
| 21 | 48723117262650147387 |
| 22 | 1074208020519710570054 |