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 | 1 |
| 3 | 0 |
| 4 | 19 |
| 5 | 0 |
| 6 | 515 |
| 7 | 0 |
| 8 | 74383 |
| 9 | 0 |
| 10 | 6816465 |
| 11 | 0 |
| 12 | 1457117673 |
| 13 | 0 |
| 14 | 241183200687 |
| 15 | 0 |
| 16 | 188350353304919 |
| 17 | 0 |
| 18 | 60855583632497865 |
| 19 | 0 |
| 20 | 39858196864723826583 |
| 21 | 0 |
| 22 | 17024263169695049621551 |
| 23 | 0 |
| 24 | 20817292362271689177123509 |
| 25 | 0 |
| 26 | 13408255577123563666760376685 |
| 27 | 0 |