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 | 6 |
| 3 | 48 |
| 4 | 516 |
| 5 | 6955 |
| 6 | 112686 |
| 7 | 2132634 |
| 8 | 46167560 |
| 9 | 1125116901 |
| 10 | 30481672610 |
| 11 | 908760877244 |
| 12 | 29565986232396 |
| 13 | 1042354163621927 |
| 14 | 39584173937284438 |
| 15 | 1610922147768721590 |
| 16 | 69940319175066857488 |
| 17 | 3226793787576474492657 |
| 18 | 157649292247463953189578 |