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 | 4 |
| 3 | 22 |
| 4 | 140 |
| 5 | 969 |
| 6 | 7084 |
| 7 | 53820 |
| 8 | 420732 |
| 9 | 3782992 |
| 10 | 32389076 |
| 11 | 275617830 |
| 12 | 2350749914 |
| 13 | 20140518790 |
| 14 | 173429992350 |
| 15 | 1500850805160 |
| 16 | 14550277251918 |
| 17 | 133009333771170 |
| 18 | 1198324107797254 |