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 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 70 |
| 9 | 1260 |
| 10 | 13650 |
| 11 | 115500 |
| 12 | 841995 |
| 13 | 5555550 |
| 14 | 34139105 |
| 15 | 198948750 |
| 16 | 1144463320 |
| 17 | 8171563400 |
| 18 | 112204064700 |
| 19 | 2364061354200 |
| 20 | 49912312090845 |
| 21 | 951208121086650 |
| 22 | 16403948060775275 |
| 23 | 260328078068154250 |
| 24 | 3860274855288458376 |
| 25 | 54182965918066177500 |