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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 27 |
| 5 | 131 |
| 6 | 497 |
| 7 | 1606 |
| 8 | 4647 |
| 9 | 12320 |
| 10 | 30493 |
| 11 | 71218 |
| 12 | 158374 |
| 13 | 337375 |
| 14 | 691981 |
| 15 | 1371917 |
| 16 | 2637956 |
| 17 | 4932911 |
| 18 | 8992413 |
| 19 | 16013007 |
| 20 | 27904818 |
| 21 | 47663115 |
| 22 | 79909497 |
| 23 | 131666339 |