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) |
|---|---|
| 2 | 1 |
| 3 | 8 |
| 4 | 52 |
| 5 | 224 |
| 6 | 1131 |
| 7 | 4620 |
| 8 | 23456 |
| 9 | 92752 |
| 10 | 460170 |
| 11 | 1805760 |
| 12 | 8946216 |
| 13 | 34942176 |
| 14 | 172593267 |
| 15 | 673129380 |
| 16 | 3323413216 |
| 17 | 12954246368 |
| 18 | 63944790462 |
| 19 | 249263001360 |
| 20 | 1230668687000 |
| 21 | 4798770328960 |
| 22 | 23700302314238 |
| 23 | 92457112946968 |
| 24 | 456814709763456 |
| 25 | 1782991313610720 |
| 26 | 8813232700137268 |