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 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 4 |
| 5 | 16 |
| 6 | 0 |
| 7 | 0 |
| 8 | 2080 |
| 9 | 32896 |
| 10 | 0 |
| 11 | 0 |
| 12 | 178990080 |
| 13 | 11453771776 |
| 14 | 0 |
| 15 | 0 |
| 16 | 3002404080455680 |
| 17 | 768614611824951296 |
| 18 | 0 |
| 19 | 0 |
| 20 | 10316167090130469587779584 |
| 21 | 10563755026498136326181748736 |
| 22 | 0 |
| 23 | 0 |
| 24 | 7561830376433501721102295492903043072 |
| 25 | 30973257220603971305905396442627825467392 |