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 | 14 |
| 4 | 88 |
| 5 | 694 |
| 6 | 6578 |
| 7 | 72792 |
| 8 | 920904 |
| 9 | 13109088 |
| 10 | 207360912 |
| 11 | 3608233056 |
| 12 | 68495486640 |
| 13 | 1408631978064 |
| 14 | 31197601660080 |
| 15 | 740303842925184 |
| 16 | 18738231641600256 |
| 17 | 503937595069600896 |
| 18 | 14349899305396086912 |
| 19 | 431322634732516137216 |
| 20 | 13646841876634025159424 |