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 | 2 |
| 2 | 7 |
| 3 | 28 |
| 4 | 142 |
| 5 | 913 |
| 6 | 7244 |
| 7 | 69004 |
| 8 | 771359 |
| 9 | 9933242 |
| 10 | 145148660 |
| 11 | 2376879719 |
| 12 | 43167728519 |
| 13 | 861914166441 |
| 14 | 18779307089740 |
| 15 | 443624137266205 |
| 16 | 11299168270825627 |
| 17 | 308780443524256478 |
| 18 | 9014690419440269085 |
| 19 | 280081388252523565158 |
| 20 | 9229143937723290061482 |