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 | 139 |
| 5 | 949 |
| 6 | 6808 |
| 7 | 50548 |
| 8 | 384916 |
| 9 | 2988418 |
| 10 | 23559826 |
| 11 | 188061592 |
| 12 | 1516680130 |
| 13 | 12337999870 |
| 14 | 101111413540 |
| 15 | 833914857316 |
| 16 | 6916004156083 |
| 17 | 57638242134229 |
| 18 | 482444724374734 |
| 19 | 4053815358183454 |
| 20 | 34181335453533439 |