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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 22 |
| 5 | 105 |
| 6 | 431 |
| 7 | 1673 |
| 8 | 6378 |
| 9 | 24237 |
| 10 | 92287 |
| 11 | 352605 |
| 12 | 1351945 |
| 13 | 5200143 |
| 14 | 20058117 |
| 15 | 77558549 |
| 16 | 300539954 |
| 17 | 1166802837 |
| 18 | 4537567343 |
| 19 | 17672631557 |
| 20 | 68923264029 |
| 21 | 269128936799 |
| 22 | 1052049481397 |
| 23 | 4116715363293 |
| 24 | 16123801840997 |
| 25 | 63205303218275 |
| 26 | 247959266473401 |
| 27 | 973469712823353 |