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 | 3 |
| 2 | 4 |
| 3 | 14 |
| 4 | 46 |
| 5 | 174 |
| 6 | 656 |
| 7 | 2640 |
| 8 | 10790 |
| 9 | 45340 |
| 10 | 193600 |
| 11 | 839820 |
| 12 | 3686424 |
| 13 | 16353924 |
| 14 | 73187456 |
| 15 | 330052646 |
| 16 | 1498335650 |
| 17 | 6841899606 |
| 18 | 31404443032 |
| 19 | 144814450188 |
| 20 | 670552118244 |
| 21 | 3116578216310 |
| 22 | 14534401932712 |
| 23 | 67992210407514 |
| 24 | 318969964124256 |
| 25 | 1500268062754830 |