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 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 1 |
| 8 | 8 |
| 9 | 36 |
| 10 | 120 |
| 11 | 330 |
| 12 | 792 |
| 13 | 1716 |
| 14 | 5148 |
| 15 | 57915 |
| 16 | 835120 |
| 17 | 9354488 |
| 18 | 84047184 |
| 19 | 638567124 |
| 20 | 4256855760 |
| 21 | 25607297880 |
| 22 | 144863655024 |
| 23 | 869425029957 |
| 24 | 7081044528888 |
| 25 | 83816629147900 |
| 26 | 1131047706331400 |
| 27 | 14634713798592030 |
| 28 | 173380501913172840 |