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 | 5 |
| 3 | 60 |
| 4 | 885 |
| 5 | 14605 |
| 6 | 258126 |
| 7 | 4778340 |
| 8 | 91460415 |
| 9 | 1795377600 |
| 10 | 35946770255 |
| 11 | 731245323256 |
| 12 | 15070729457030 |
| 13 | 314011160190675 |
| 14 | 6603561278126200 |
| 15 | 139980599432879480 |
| 16 | 2987856960226960551 |
| 17 | 64162892863813071450 |
| 18 | 1385270621375211268550 |