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) |
|---|---|
| 1 | 5 |
| 2 | 25 |
| 3 | 125 |
| 4 | 620 |
| 5 | 3060 |
| 6 | 15040 |
| 7 | 73680 |
| 8 | 360000 |
| 9 | 1755200 |
| 10 | 8542720 |
| 11 | 41519360 |
| 12 | 201559040 |
| 13 | 977556480 |
| 14 | 4737433600 |
| 15 | 22943846400 |
| 16 | 111060664320 |
| 17 | 537360220160 |
| 18 | 2599052247040 |
| 19 | 12567124705280 |
| 20 | 60750607155200 |
| 21 | 293614524825600 |