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 | 4 |
| 2 | 26 |
| 3 | 224 |
| 4 | 2389 |
| 5 | 30324 |
| 6 | 446109 |
| 7 | 7460928 |
| 8 | 139775763 |
| 9 | 2899264620 |
| 10 | 65954625560 |
| 11 | 1632654953280 |
| 12 | 43688087178059 |
| 13 | 1256602120453484 |
| 14 | 38661480001233486 |
| 15 | 1266934683224418816 |
| 16 | 44054989554206606603 |
| 17 | 1620147926716343851500 |
| 18 | 62826169539072988352134 |
| 19 | 2562071016044926371845920 |
| 20 | 109611597248567432265872903 |
| 21 | 4908887251696851858305862332 |