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 | 10 |
| 3 | 74 |
| 4 | 515 |
| 5 | 3540 |
| 6 | 24276 |
| 7 | 166405 |
| 8 | 1140574 |
| 9 | 7817630 |
| 10 | 53582855 |
| 11 | 367262376 |
| 12 | 2517253800 |
| 13 | 17253514249 |
| 14 | 118257345970 |
| 15 | 810547907570 |
| 16 | 5555578007051 |
| 17 | 38078498141820 |
| 18 | 260993908985724 |
| 19 | 1788878864758285 |
| 20 | 12261158144322310 |