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 | 1 |
| 4 | 5 |
| 5 | 21 |
| 6 | 81 |
| 7 | 295 |
| 8 | 1037 |
| 9 | 3555 |
| 10 | 11961 |
| 11 | 39667 |
| 12 | 130049 |
| 13 | 422403 |
| 14 | 1361385 |
| 15 | 4359115 |
| 16 | 13880129 |
| 17 | 43984227 |
| 18 | 138795849 |
| 19 | 436367131 |
| 20 | 1367434577 |
| 21 | 4272615603 |
| 22 | 13315096089 |
| 23 | 41397076939 |
| 24 | 128429930465 |
| 25 | 397665266595 |
| 26 | 1229127726825 |
| 27 | 3792875384251 |
| 28 | 11686625364785 |