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 | 12 |
| 2 | 108 |
| 3 | 880 |
| 4 | 6855 |
| 5 | 52164 |
| 6 | 391720 |
| 7 | 2918304 |
| 8 | 21634290 |
| 9 | 159880600 |
| 10 | 1179180552 |
| 11 | 8685874080 |
| 12 | 63930198787 |
| 13 | 470327654580 |
| 14 | 3459353475600 |
| 15 | 25442360389696 |
| 16 | 187126561024686 |
| 17 | 1376455855989672 |
| 18 | 10126540146288520 |
| 19 | 74515694338112160 |
| 20 | 548444877468906726 |