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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 719 |
| 7 | 5022 |
| 8 | 40064 |
| 9 | 359400 |
| 10 | 3580896 |
| 11 | 39233867 |
| 12 | 468818397 |
| 13 | 6067548429 |
| 14 | 84551873634 |
| 15 | 1262188317534 |
| 16 | 20095114167065 |
| 17 | 339883289813330 |
| 18 | 6086154606429378 |
| 19 | 115025120586250896 |
| 20 | 2288119443771888504 |
| 21 | 47787869441095495395 |
| 22 | 1045507132393256095282 |