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 | 0 |
| 2 | 7 |
| 3 | 58 |
| 4 | 286 |
| 5 | 3068 |
| 6 | 29876 |
| 7 | 214485 |
| 8 | 1910822 |
| 9 | 17671945 |
| 10 | 141365332 |
| 11 | 1225043571 |
| 12 | 10871708273 |
| 13 | 90688536786 |
| 14 | 781019641877 |
| 15 | 6800784990468 |
| 16 | 57716277595775 |
| 17 | 496096480109463 |
| 18 | 4284929501626939 |
| 19 | 36621478929328140 |
| 20 | 314572431365390797 |
| 21 | 2707867101849205129 |