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 | 1 |
| 2 | 5 |
| 3 | 28 |
| 4 | 200 |
| 5 | 1805 |
| 6 | 19861 |
| 7 | 258200 |
| 8 | 3873008 |
| 9 | 65841145 |
| 10 | 1250981765 |
| 11 | 26270617076 |
| 12 | 604224192760 |
| 13 | 15105604819013 |
| 14 | 407851330113365 |
| 15 | 11827688573287600 |
| 16 | 366658345771915616 |
| 17 | 12099725410473215345 |
| 18 | 423490389366562537093 |
| 19 | 15669144406562813872460 |