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 | 4 |
| 3 | 175 |
| 4 | 3324 |
| 5 | 42469 |
| 6 | 429120 |
| 7 | 3711027 |
| 8 | 28723640 |
| 9 | 204598130 |
| 10 | 1366223880 |
| 11 | 8664086470 |
| 12 | 52673351080 |
| 13 | 309164754285 |
| 14 | 1761471681568 |
| 15 | 9783594370723 |
| 16 | 53154274959360 |
| 17 | 283267669144390 |
| 18 | 1484104565936920 |
| 19 | 7658877239935362 |
| 20 | 38993558097982312 |
| 21 | 196127054929939810 |