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 | 0 |
| 1 | 1 |
| 2 | 19 |
| 3 | 271 |
| 4 | 3439 |
| 5 | 40951 |
| 6 | 468559 |
| 7 | 434062 |
| 8 | 13906558 |
| 9 | 225159022 |
| 10 | 3026431198 |
| 11 | 5856821173 |
| 12 | 152711390557 |
| 13 | 2374402515013 |
| 14 | 8492830180156 |
| 15 | 176435471621404 |
| 16 | 734899055740795 |
| 17 | 16614091501667155 |
| 18 | 99432188218005274 |
| 19 | 544037976289055377 |
| 20 | 2738676327544569592 |