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 | 12 |
| 3 | 133 |
| 4 | 1464 |
| 5 | 16215 |
| 6 | 178366 |
| 7 | 2073137 |
| 8 | 22814518 |
| 9 | 252060710 |
| 10 | 2772667811 |
| 11 | 31610457022 |
| 12 | 347715137243 |
| 13 | 3835866520674 |
| 14 | 43305642727525 |
| 15 | 476363171113776 |
| 16 | 5351104882252647 |
| 17 | 58862154814780228 |
| 18 | 658583714063682520 |
| 19 | 7355531854711617721 |
| 20 | 82021851512827806032 |