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 | 4 |
| 5 | 24 |
| 6 | 144 |
| 7 | 744 |
| 8 | 3844 |
| 9 | 19344 |
| 10 | 97344 |
| 11 | 487344 |
| 12 | 2439844 |
| 13 | 12202344 |
| 14 | 61027344 |
| 15 | 305152344 |
| 16 | 1525839844 |
| 17 | 7629277344 |
| 18 | 38146777344 |
| 19 | 190734277344 |
| 20 | 953673339844 |
| 21 | 4768368652344 |
| 22 | 23841853027344 |
| 23 | 119209274902344 |
| 24 | 596046423339844 |
| 25 | 2980232165527344 |
| 26 | 14901161071777344 |
| 27 | 74505805603027344 |