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 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 52 |
| 5 | 472 |
| 6 | 5504 |
| 7 | 78416 |
| 8 | 1320064 |
| 9 | 25637824 |
| 10 | 564275648 |
| 11 | 13879795712 |
| 12 | 377332365568 |
| 13 | 11234698041088 |
| 14 | 363581406419456 |
| 15 | 12707452084972544 |
| 16 | 477027941930515456 |
| 17 | 19142041172838025216 |
| 18 | 817675811320888020992 |
| 19 | 37044610820729973813248 |
| 20 | 1774189422608238694776832 |