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 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 2 |
| 7 | 34 |
| 8 | 382 |
| 9 | 3518 |
| 10 | 28708 |
| 11 | 216098 |
| 12 | 1536960 |
| 13 | 10488708 |
| 14 | 69393216 |
| 15 | 448301130 |
| 16 | 2842611306 |
| 17 | 17758399872 |
| 18 | 109613418746 |
| 19 | 669950441982 |
| 20 | 4061411038376 |
| 21 | 24453911859134 |
| 22 | 146393798673526 |
| 23 | 872121958672162 |
| 24 | 5173931524573894 |
| 25 | 30584965562156650 |