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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 15 |
| 5 | 86 |
| 6 | 544 |
| 7 | 3934 |
| 8 | 32079 |
| 9 | 292509 |
| 10 | 2952702 |
| 11 | 32712087 |
| 12 | 394749367 |
| 13 | 5155010088 |
| 14 | 72440184064 |
| 15 | 1090017765544 |
| 16 | 17486996858151 |
| 17 | 297965879586295 |
| 18 | 5374189975316350 |
| 19 | 102290550351854445 |
| 20 | 2049025241258716927 |
| 21 | 43089888746430771294 |
| 22 | 949172134240270646352 |