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 | 3 |
| 4 | 13 |
| 5 | 67 |
| 6 | 264 |
| 7 | 1667 |
| 8 | 16667 |
| 9 | 94863 |
| 10 | 1643167 |
| 11 | 29983327 |
| 12 | 706399164 |
| 13 | 31144643167 |
| 14 | 1296109172867 |
| 15 | 62441868958167 |
| 16 | 6927459779738887 |
| 17 | 447213595487659543 |
| 18 | 77453069648658793167 |
| 19 | 14104963594032775808167 |
| 20 | 3146266035952345970972687 |