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 | 1 |
| 3 | 8 |
| 4 | 63 |
| 5 | 664 |
| 6 | 7462 |
| 7 | 90896 |
| 8 | 1159587 |
| 9 | 15369761 |
| 10 | 209785576 |
| 11 | 2933152208 |
| 12 | 41833725570 |
| 13 | 606735330572 |
| 14 | 8926655086328 |
| 15 | 132969013796640 |
| 16 | 2002168332793035 |
| 17 | 30435351234214599 |
| 18 | 466570991414368225 |
| 19 | 7206553709798780480 |
| 20 | 112066631802051120600 |
| 21 | 1753396593921234013664 |