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 | 4 |
| 2 | 36 |
| 3 | 400 |
| 4 | 4900 |
| 5 | 63504 |
| 6 | 853776 |
| 7 | 11778624 |
| 8 | 165636900 |
| 9 | 2363904400 |
| 10 | 34134779536 |
| 11 | 497634306624 |
| 12 | 7312459672336 |
| 13 | 108172480360000 |
| 14 | 1609341595560000 |
| 15 | 24061445010950400 |
| 16 | 361297635242552100 |
| 17 | 5445717990022688400 |
| 18 | 82358080713306090000 |
| 19 | 1249287673091590440000 |