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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 46 |
| 5 | 534 |
| 6 | 7596 |
| 7 | 127756 |
| 8 | 2479856 |
| 9 | 54560512 |
| 10 | 1341716960 |
| 11 | 36468949824 |
| 12 | 1085680795200 |
| 13 | 35131589529152 |
| 14 | 1227777836217856 |
| 15 | 46086892351150592 |
| 16 | 1849266301464495616 |
| 17 | 78990342571085637120 |
| 18 | 3578513340735623076864 |