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 | 2 |
| 2 | 1 |
| 3 | 4 |
| 4 | 8 |
| 5 | 24 |
| 6 | 56 |
| 7 | 156 |
| 8 | 400 |
| 9 | 1092 |
| 10 | 2928 |
| 11 | 8052 |
| 12 | 22080 |
| 13 | 61320 |
| 14 | 170664 |
| 15 | 478288 |
| 16 | 1344800 |
| 17 | 3798240 |
| 18 | 10760568 |
| 19 | 30585828 |
| 20 | 87166656 |
| 21 | 249055976 |
| 22 | 713197848 |
| 23 | 2046590844 |
| 24 | 5883926400 |
| 25 | 16945772184 |
| 26 | 48881973840 |
| 27 | 141214767876 |
| 28 | 408513980160 |
| 29 | 1183282368360 |
| 30 | 3431518388960 |