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 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 7 |
| 8 | 1 |
| 9 | 0 |
| 10 | 0 |
| 11 | 9240 |
| 12 | 34650 |
| 13 | 1716 |
| 14 | 48477 |
| 15 | 551915 |
| 16 | 6726720 |
| 17 | 89973520 |
| 18 | 102639744 |
| 19 | 1824625081 |
| 20 | 9915389400 |
| 21 | 30143458884 |
| 22 | 278196062760 |
| 23 | 1995766236541 |
| 24 | 6611689457736 |
| 25 | 64547920386450 |
| 26 | 236756174748626 |
| 27 | 2315743488707806 |