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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 2 |
| 6 | 9 |
| 7 | 31 |
| 8 | 147 |
| 9 | 809 |
| 10 | 5855 |
| 11 | 54477 |
| 12 | 633057 |
| 13 | 8724874 |
| 14 | 137047391 |
| 15 | 2391169355 |
| 16 | 45626910415 |
| 17 | 942659626031 |
| 18 | 20937539944549 |
| 19 | 497209670658529 |
| 20 | 12566853576025106 |
| 21 | 336749273734805530 |
| 22 | 9534909974420181226 |