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 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 4 |
| 7 | 8 |
| 8 | 16 |
| 9 | 48 |
| 10 | 144 |
| 11 | 432 |
| 12 | 1296 |
| 13 | 5184 |
| 14 | 20736 |
| 15 | 82944 |
| 16 | 331776 |
| 17 | 1658880 |
| 18 | 8294400 |
| 19 | 41472000 |
| 20 | 207360000 |
| 21 | 1244160000 |
| 22 | 7464960000 |
| 23 | 44789760000 |
| 24 | 268738560000 |
| 25 | 1881169920000 |
| 26 | 13168189440000 |
| 27 | 92177326080000 |
| 28 | 645241282560000 |
| 29 | 5161930260480000 |