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 | 54 |
| 4 | 680 |
| 5 | 11000 |
| 6 | 217392 |
| 7 | 5076400 |
| 8 | 136761984 |
| 9 | 4175432064 |
| 10 | 142469423360 |
| 11 | 5372711277824 |
| 12 | 221903307604992 |
| 13 | 9961821300640768 |
| 14 | 482982946946734080 |
| 15 | 25150966159083264000 |
| 16 | 1400031335107317628928 |
| 17 | 82960293298087664648192 |