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 | 2 |
| 3 | 5 |
| 4 | 18 |
| 5 | 105 |
| 6 | 902 |
| 7 | 9749 |
| 8 | 127072 |
| 9 | 1915951 |
| 10 | 32743182 |
| 11 | 624999093 |
| 12 | 13176573910 |
| 13 | 304072048265 |
| 14 | 7623505722158 |
| 15 | 206342800616597 |
| 16 | 5996837126024824 |
| 17 | 186254702826289089 |
| 18 | 6156752656678674792 |
| 19 | 215810382466145354405 |
| 20 | 7995774669504366055054 |