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 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 40 |
| 5 | 208 |
| 6 | 928 |
| 7 | 3904 |
| 8 | 16000 |
| 9 | 64768 |
| 10 | 260608 |
| 11 | 1045504 |
| 12 | 4188160 |
| 13 | 16764928 |
| 14 | 67084288 |
| 15 | 268386304 |
| 16 | 1073643520 |
| 17 | 4294770688 |
| 18 | 17179475968 |
| 19 | 68718690304 |
| 20 | 274876334080 |
| 21 | 1099508482048 |
| 22 | 4398040219648 |
| 23 | 17592173461504 |
| 24 | 70368719011840 |
| 25 | 281474926379008 |