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 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 9 |
| 5 | 44 |
| 6 | 265 |
| 7 | 1854 |
| 8 | 14833 |
| 9 | 133496 |
| 10 | 1334961 |
| 11 | 11881152 |
| 12 | 95568369 |
| 13 | 709693034 |
| 14 | 4983272692 |
| 15 | 33840285766 |
| 16 | 226398597533 |
| 17 | 1513188564484 |
| 18 | 10205785143785 |
| 19 | 69950515246416 |
| 20 | 489604464034696 |
| 21 | 3472020025514928 |
| 22 | 24798829697691764 |
| 23 | 177618356951602784 |