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 | 7 |
| 2 | 38 |
| 3 | 222 |
| 4 | 1464 |
| 5 | 10920 |
| 6 | 91440 |
| 7 | 851760 |
| 8 | 8749440 |
| 9 | 98340480 |
| 10 | 1201132800 |
| 11 | 15846969600 |
| 12 | 224651750400 |
| 13 | 3406180377600 |
| 14 | 55009501747200 |
| 15 | 942833219328000 |
| 16 | 17093919338496000 |
| 17 | 326876746420224000 |
| 18 | 6575237795782656000 |