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 | 18 |
| 3 | 165 |
| 4 | 2016 |
| 5 | 30807 |
| 6 | 564912 |
| 7 | 12085713 |
| 8 | 295498368 |
| 9 | 8128142667 |
| 10 | 248419104768 |
| 11 | 8351633349117 |
| 12 | 306299582106624 |
| 13 | 12169801665625887 |
| 14 | 520721224401217536 |
| 15 | 23872081186754865513 |
| 16 | 1167357853571179216896 |
| 17 | 60652216264444277244435 |
| 18 | 3336667444310413833732096 |