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 | 3 |
| 2 | 21 |
| 3 | 217 |
| 4 | 2904 |
| 5 | 47337 |
| 6 | 906557 |
| 7 | 19910808 |
| 8 | 492818850 |
| 9 | 13564326950 |
| 10 | 410807572044 |
| 11 | 13573135469214 |
| 12 | 485765085176420 |
| 13 | 18717987193565613 |
| 14 | 772565258231236269 |
| 15 | 34002334709760133807 |
| 16 | 1589555183231724515700 |