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 | 5 |
| 3 | 56 |
| 4 | 1020 |
| 5 | 26015 |
| 6 | 855478 |
| 7 | 34461260 |
| 8 | 1642995124 |
| 9 | 90456911140 |
| 10 | 5646312067585 |
| 11 | 393937815588880 |
| 12 | 30374808071994000 |
| 13 | 2564601377235725520 |
| 14 | 235302361169390146650 |
| 15 | 23309583579201438877060 |