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 | 0 |
| 3 | 1 |
| 4 | 3 |
| 5 | 3 |
| 6 | 8 |
| 7 | 30 |
| 8 | 117 |
| 9 | 466 |
| 10 | 1960 |
| 11 | 8655 |
| 12 | 40391 |
| 13 | 200085 |
| 14 | 1051888 |
| 15 | 5844844 |
| 16 | 34131049 |
| 17 | 208344660 |
| 18 | 1324262256 |
| 19 | 8743620525 |
| 20 | 59891078347 |
| 21 | 425216195191 |
| 22 | 3126418416440 |
| 23 | 23778261543210 |
| 24 | 186815245299549 |
| 25 | 1513931016854598 |