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 | 3 |
| 2 | 270 |
| 3 | 20160 |
| 4 | 1477980 |
| 5 | 108097935 |
| 6 | 7903526400 |
| 7 | 577834413429 |
| 8 | 42245731959480 |
| 9 | 3088601154192960 |
| 10 | 225808743709815750 |
| 11 | 16508958287605688193 |
| 12 | 1206975861055570636800 |
| 13 | 88242438021480689844999 |
| 14 | 6451436286916714206370530 |
| 15 | 471666820375043557337304000 |