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 | 20 |
| 2 | 240 |
| 3 | 2200 |
| 4 | 16940 |
| 5 | 115104 |
| 6 | 711040 |
| 7 | 4072640 |
| 8 | 21930480 |
| 9 | 112157760 |
| 10 | 549010176 |
| 11 | 2587777920 |
| 12 | 11802273600 |
| 13 | 52287866880 |
| 14 | 225756241920 |
| 15 | 952486588416 |
| 16 | 3935984616960 |
| 17 | 15961485957120 |
| 18 | 63628396339200 |
| 19 | 249702113464320 |
| 20 | 965924035135488 |
| 21 | 3687247950397440 |