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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 6 |
| 4 | 20 |
| 5 | 60 |
| 6 | 168 |
| 7 | 448 |
| 8 | 1152 |
| 9 | 2880 |
| 10 | 7040 |
| 11 | 16896 |
| 12 | 39936 |
| 13 | 93184 |
| 14 | 215040 |
| 15 | 491520 |
| 16 | 1114112 |
| 17 | 2506752 |
| 18 | 5603328 |
| 19 | 12451840 |
| 20 | 27525120 |
| 21 | 60555264 |
| 22 | 132644864 |
| 23 | 289406976 |
| 24 | 629145600 |
| 25 | 1363148800 |
| 26 | 2944401408 |
| 27 | 6341787648 |
| 28 | 13623099392 |
| 29 | 29192355840 |
| 30 | 62411243520 |