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 | 54 |
| 2 | 1431 |
| 3 | 24804 |
| 4 | 316251 |
| 5 | 3162510 |
| 6 | 25827165 |
| 7 | 177100560 |
| 8 | 1040465790 |
| 9 | 5317936260 |
| 10 | 23930713170 |
| 11 | 95722852680 |
| 12 | 343006888770 |
| 13 | 1108176102180 |
| 14 | 3245372870670 |
| 15 | 8654327655120 |
| 16 | 21094923659355 |
| 17 | 47153358767970 |
| 18 | 96926348578605 |
| 19 | 183649923622620 |
| 20 | 321387366339585 |