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 | 3 |
| 4 | 24 |
| 5 | 135 |
| 6 | 657 |
| 7 | 2961 |
| 8 | 12744 |
| 9 | 53244 |
| 10 | 218025 |
| 11 | 880308 |
| 12 | 3518721 |
| 13 | 13961727 |
| 14 | 55097091 |
| 15 | 216546048 |
| 16 | 848476296 |
| 17 | 3316800555 |
| 18 | 12942852624 |
| 19 | 50437433079 |
| 20 | 196347606849 |
| 21 | 763752142233 |
| 22 | 2969021213928 |
| 23 | 11536374392820 |
| 24 | 44809232564673 |
| 25 | 173997851613660 |
| 26 | 675501426136017 |