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 | 2 |
| 5 | 0 |
| 6 | 12 |
| 7 | 0 |
| 8 | 40 |
| 9 | 10 |
| 10 | 516 |
| 11 | 124 |
| 12 | 5020 |
| 13 | 1828 |
| 14 | 48570 |
| 15 | 32806 |
| 16 | 527890 |
| 17 | 444480 |
| 18 | 6137942 |
| 19 | 6482314 |
| 20 | 70573856 |
| 21 | 93276044 |
| 22 | 853480374 |
| 23 | 1300190254 |
| 24 | 10660384742 |
| 25 | 18371629260 |
| 26 | 134129890382 |
| 27 | 259804151324 |
| 28 | 1728886287134 |
| 29 | 3667061002286 |
| 30 | 22672130669968 |