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 | 7 |
| 3 | 52 |
| 4 | 472 |
| 5 | 5197 |
| 6 | 67567 |
| 7 | 1013512 |
| 8 | 17229712 |
| 9 | 327364537 |
| 10 | 6874655287 |
| 11 | 158117071612 |
| 12 | 3952926790312 |
| 13 | 106729023338437 |
| 14 | 3095141676814687 |
| 15 | 95949391981255312 |
| 16 | 3166329935381425312 |
| 17 | 110821547738349885937 |
| 18 | 4100397266318945779687 |
| 19 | 159915493386438885407812 |