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 | 4 |
| 3 | 25 |
| 4 | 224 |
| 5 | 2601 |
| 6 | 37072 |
| 7 | 626137 |
| 8 | 12232320 |
| 9 | 271494865 |
| 10 | 6750538496 |
| 11 | 185923318329 |
| 12 | 5619645500416 |
| 13 | 184961854976185 |
| 14 | 6585429015521280 |
| 15 | 252203521861645561 |
| 16 | 10338251689510381568 |
| 17 | 451650823526438037153 |
| 18 | 20949317446607098716160 |
| 19 | 1028215744082428119960025 |