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 | 9 |
| 2 | 78 |
| 3 | 678 |
| 4 | 5892 |
| 5 | 51204 |
| 6 | 444984 |
| 7 | 3867096 |
| 8 | 33606672 |
| 9 | 292055952 |
| 10 | 2538087648 |
| 11 | 22057036896 |
| 12 | 191684821056 |
| 13 | 1665820789824 |
| 14 | 14476675244928 |
| 15 | 125808326698368 |
| 16 | 1093326665056512 |
| 17 | 9501463280642304 |
| 18 | 82571666235477504 |
| 19 | 717582109567673856 |
| 20 | 6236086873954255872 |