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 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 16 |
| 4 | 68 |
| 5 | 287 |
| 6 | 1208 |
| 7 | 5088 |
| 8 | 21432 |
| 9 | 90273 |
| 10 | 380236 |
| 11 | 1601584 |
| 12 | 6745996 |
| 13 | 28414655 |
| 14 | 119684720 |
| 15 | 504121280 |
| 16 | 2123397744 |
| 17 | 8943915201 |
| 18 | 37672461204 |
| 19 | 158679314512 |
| 20 | 668369521108 |
| 21 | 2815224014047 |
| 22 | 11857940853032 |
| 23 | 49946562182048 |
| 24 | 210378775263272 |
| 25 | 886131640451169 |