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 | 2 |
| 3 | 9 |
| 4 | 72 |
| 5 | 880 |
| 6 | 14946 |
| 7 | 331177 |
| 8 | 9157984 |
| 9 | 305879724 |
| 10 | 12036430600 |
| 11 | 547226046939 |
| 12 | 28298540270928 |
| 13 | 1643380366183920 |
| 14 | 106042236588594096 |
| 15 | 7535372761616117625 |
| 16 | 585204851983514095424 |
| 17 | 49344635724104556446660 |
| 18 | 4491848127809479571999928 |
| 19 | 439231681095730953672503448 |