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 | 19 |
| 4 | 118 |
| 5 | 886 |
| 6 | 7786 |
| 7 | 78184 |
| 8 | 881644 |
| 9 | 11017108 |
| 10 | 150966856 |
| 11 | 2249261356 |
| 12 | 36181351504 |
| 13 | 624658612384 |
| 14 | 11516406883528 |
| 15 | 225740649754936 |
| 16 | 4686671645814736 |
| 17 | 102712289940757264 |
| 18 | 2369128149877075264 |
| 19 | 57359541280704038128 |
| 20 | 1454229915957292684576 |