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) |
|---|---|
| 3 | 1 |
| 4 | 1 |
| 5 | 5 |
| 6 | 20 |
| 7 | 117 |
| 8 | 791 |
| 9 | 6205 |
| 10 | 55004 |
| 11 | 543597 |
| 12 | 5922929 |
| 13 | 70518905 |
| 14 | 910711192 |
| 15 | 12678337945 |
| 16 | 189252400479 |
| 17 | 3015217932073 |
| 18 | 51067619064872 |
| 19 | 916176426422089 |
| 20 | 17355904144773969 |
| 21 | 346195850534379613 |
| 22 | 7252654441500887308 |
| 23 | 159210363453697619309 |
| 24 | 3654550890669678498263 |