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 | 5 |
| 2 | 30 |
| 3 | 220 |
| 4 | 1775 |
| 5 | 15206 |
| 6 | 135745 |
| 7 | 1248900 |
| 8 | 11758240 |
| 9 | 112736305 |
| 10 | 1096960024 |
| 11 | 10804727805 |
| 12 | 107520029780 |
| 13 | 1079346767060 |
| 14 | 10917110317185 |
| 15 | 111149886462926 |
| 16 | 1138205538056395 |
| 17 | 11715403351807780 |
| 18 | 121137702435412040 |
| 19 | 1257720947476195045 |
| 20 | 13106870738511517659 |