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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 68 |
| 5 | 725 |
| 6 | 9942 |
| 7 | 166453 |
| 8 | 3290632 |
| 9 | 75017097 |
| 10 | 1937420010 |
| 11 | 55906879809 |
| 12 | 1782695466444 |
| 13 | 62247810769053 |
| 14 | 2362246665531326 |
| 15 | 96806321000599725 |
| 16 | 4260677055123222544 |
| 17 | 200440759819510706321 |
| 18 | 10037364633737549049042 |
| 19 | 533071599267242747118585 |