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 | 1 |
| 2 | 21 |
| 3 | 362 |
| 4 | 6026 |
| 5 | 101524 |
| 6 | 1763100 |
| 7 | 31813200 |
| 8 | 598482000 |
| 9 | 11752855200 |
| 10 | 240947474400 |
| 11 | 5154170774400 |
| 12 | 114942011990400 |
| 13 | 2669517204076800 |
| 14 | 64496340380102400 |
| 15 | 1619153396908185600 |
| 16 | 42188624389562112000 |