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 | 23 |
| 4 | 201 |
| 5 | 2529 |
| 6 | 36027 |
| 7 | 633975 |
| 8 | 12445521 |
| 9 | 282376065 |
| 10 | 7045758003 |
| 11 | 196111046295 |
| 12 | 5929900611225 |
| 13 | 195773173735905 |
| 14 | 6950809317622635 |
| 15 | 265652001656970615 |
| 16 | 10828342476187312545 |
| 17 | 470368564694268015105 |
| 18 | 21643209863062015977315 |
| 19 | 1053344875062427351601175 |