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 | 1 |
| 2 | 21 |
| 3 | 637 |
| 4 | 22295 |
| 5 | 842751 |
| 6 | 33429123 |
| 7 | 1370594043 |
| 8 | 57564949806 |
| 9 | 2462500630590 |
| 10 | 106872527367606 |
| 11 | 4692675519868518 |
| 12 | 208041948047504298 |
| 13 | 9297874755046153626 |
| 14 | 418404363977076913170 |
| 15 | 18939770876029014936162 |
| 16 | 861759574859320179595371 |
| 17 | 39387481745040692914447251 |