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 | 1 |
| 2 | 5 |
| 3 | 32 |
| 4 | 239 |
| 5 | 1981 |
| 6 | 17757 |
| 7 | 169765 |
| 8 | 1717730 |
| 9 | 18311250 |
| 10 | 205075693 |
| 11 | 2408303246 |
| 12 | 29611689597 |
| 13 | 380712483013 |
| 14 | 5111573917042 |
| 15 | 71576222215342 |
| 16 | 1043901890068909 |
| 17 | 15835797676490439 |
| 18 | 249530033466698385 |
| 19 | 4078781718332965858 |