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 | 6 |
| 3 | 54 |
| 4 | 660 |
| 5 | 10255 |
| 6 | 193732 |
| 7 | 4312980 |
| 8 | 110598510 |
| 9 | 3210608808 |
| 10 | 104085718451 |
| 11 | 3727491264497 |
| 12 | 146140031249576 |
| 13 | 6225801069767760 |
| 14 | 286376011804522536 |
| 15 | 14145748008085964988 |
| 16 | 746808042116142422388 |
| 17 | 41964968782188114180606 |
| 18 | 2500755433211714966201145 |