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 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 19 |
| 6 | 85 |
| 7 | 509 |
| 8 | 4060 |
| 9 | 41301 |
| 10 | 510489 |
| 11 | 7319447 |
| 12 | 117940535 |
| 13 | 2094480864 |
| 14 | 40497138011 |
| 15 | 845480228069 |
| 16 | 18941522184590 |
| 17 | 453090162062723 |
| 18 | 11523392072541432 |
| 19 | 310467244165539782 |
| 20 | 8832736318937756165 |