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 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 19 |
| 5 | 230 |
| 6 | 5098 |
| 7 | 207536 |
| 8 | 15891372 |
| 9 | 2343580752 |
| 10 | 675458276144 |
| 11 | 383306076989440 |
| 12 | 430041136692146912 |
| 13 | 956431386434331323776 |
| 14 | 4224539434553753578497024 |
| 15 | 37106501188130085159785113344 |
| 16 | 648740172906485727983524271405824 |
| 17 | 22591360806791558877526051411343415296 |
| 18 | 1567817808096346724727108606144936617617408 |