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 | 0 |
| 2 | 63 |
| 3 | 702 |
| 4 | 6525 |
| 5 | 59004 |
| 6 | 531387 |
| 7 | 4782906 |
| 8 | 43046649 |
| 9 | 387420408 |
| 10 | 3486784311 |
| 11 | 31381059510 |
| 12 | 282429536373 |
| 13 | 2541865828212 |
| 14 | 22876792454835 |
| 15 | 205891132094514 |
| 16 | 1853020188851697 |
| 17 | 16677181699666416 |
| 18 | 150094635296998959 |
| 19 | 1350851717672991918 |
| 20 | 12157665459056928621 |
| 21 | 109418989131512359020 |