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 | 3 |
| 3 | 10 |
| 4 | 36 |
| 5 | 135 |
| 6 | 525 |
| 7 | 2094 |
| 8 | 8524 |
| 9 | 35266 |
| 10 | 147862 |
| 11 | 626884 |
| 12 | 2682940 |
| 13 | 11575707 |
| 14 | 50295809 |
| 15 | 219879814 |
| 16 | 966487380 |
| 17 | 4268781902 |
| 18 | 18936044682 |
| 19 | 84326759820 |
| 20 | 376853237480 |
| 21 | 1689551241606 |
| 22 | 7597003401186 |
| 23 | 34251504489484 |