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 | 0 |
| 5 | 0 |
| 6 | 5 |
| 7 | 14 |
| 8 | 28 |
| 9 | 90 |
| 10 | 285 |
| 11 | 1232 |
| 12 | 4378 |
| 13 | 17082 |
| 14 | 65338 |
| 15 | 269775 |
| 16 | 1148080 |
| 17 | 5111730 |
| 18 | 23047359 |
| 19 | 107594036 |
| 20 | 507358368 |
| 21 | 2479868846 |
| 22 | 12286215326 |
| 23 | 62819732813 |
| 24 | 325860325750 |
| 25 | 1733254403460 |
| 26 | 9356359893725 |
| 27 | 51583509113814 |
| 28 | 288761957868348 |
| 29 | 1647416875806320 |