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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 13 |
| 5 | 94 |
| 6 | 866 |
| 7 | 9652 |
| 8 | 126689 |
| 9 | 1914412 |
| 10 | 32736453 |
| 11 | 624968662 |
| 12 | 13176422634 |
| 13 | 304071291562 |
| 14 | 7623501667031 |
| 15 | 206342778454312 |
| 16 | 5996836998828457 |
| 17 | 186254702081260312 |
| 18 | 6156752652130549218 |
| 19 | 215810382437839251562 |
| 20 | 7995774669321944270390 |
| 21 | 312215963278285442939062 |