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 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 18 |
| 5 | 50 |
| 6 | 215 |
| 7 | 735 |
| 8 | 2898 |
| 9 | 10668 |
| 10 | 41202 |
| 11 | 156090 |
| 12 | 601623 |
| 13 | 2308878 |
| 14 | 8923343 |
| 15 | 34487453 |
| 16 | 133749330 |
| 17 | 519277512 |
| 18 | 2020262660 |
| 19 | 7869597840 |
| 20 | 30699524018 |
| 21 | 119894389380 |
| 22 | 468768069882 |
| 23 | 1834589752182 |
| 24 | 7186572436887 |
| 25 | 28175111736300 |
| 26 | 110547143014050 |
| 27 | 434049816801900 |