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 | 11 |
| 2 | 107 |
| 3 | 1066 |
| 4 | 11274 |
| 5 | 127860 |
| 6 | 1557660 |
| 7 | 20355120 |
| 8 | 284574960 |
| 9 | 4243508640 |
| 10 | 67285058400 |
| 11 | 1131047366400 |
| 12 | 20099588140800 |
| 13 | 376612896038400 |
| 14 | 7422410595801600 |
| 15 | 153516757766400000 |
| 16 | 3325222830101760000 |
| 17 | 75283691519393280000 |
| 18 | 1778358268603445760000 |