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 | 3 |
| 2 | 24 |
| 3 | 280 |
| 4 | 4044 |
| 5 | 67365 |
| 6 | 1246534 |
| 7 | 25051422 |
| 8 | 538836147 |
| 9 | 12279937669 |
| 10 | 294374405652 |
| 11 | 7382843258466 |
| 12 | 192917842671564 |
| 13 | 5235276617405133 |
| 14 | 147163222059602313 |
| 15 | 4275948043251399950 |
| 16 | 128196303568520249238 |
| 17 | 3959890522003241945409 |
| 18 | 125863828745364900374059 |