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) |
|---|---|
| 2 | 2 |
| 3 | 0 |
| 4 | 8 |
| 5 | 0 |
| 6 | 32 |
| 7 | 0 |
| 8 | 128 |
| 9 | 0 |
| 10 | 2560 |
| 11 | 0 |
| 12 | 1415168 |
| 13 | 0 |
| 14 | 57344 |
| 15 | 0 |
| 16 | 118521856 |
| 17 | 0 |
| 18 | 5749735424 |
| 19 | 0 |
| 20 | 91546451968 |
| 21 | 0 |
| 22 | 1792043646976 |
| 23 | 0 |
| 24 | 1982765704675328 |
| 25 | 0 |
| 26 | 286994513002496 |
| 27 | 0 |
| 28 | 3187598700536922112 |
| 29 | 0 |
| 30 | 4625594563496048066560 |