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 | 72 |
| 2 | 2556 |
| 3 | 59640 |
| 4 | 1028790 |
| 5 | 13991544 |
| 6 | 156238908 |
| 7 | 1473109704 |
| 8 | 11969016345 |
| 9 | 85113005120 |
| 10 | 536211932256 |
| 11 | 3022285436352 |
| 12 | 15363284301456 |
| 13 | 70907466006720 |
| 14 | 298824321028320 |
| 15 | 1155454041309504 |
| 16 | 4116305022165108 |
| 17 | 13559593014190944 |
| 18 | 41432089765583440 |