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 | 0 |
| 5 | 12 |
| 6 | 150 |
| 7 | 1200 |
| 8 | 7845 |
| 9 | 46280 |
| 10 | 254676 |
| 11 | 1344900 |
| 12 | 6892425 |
| 13 | 34646220 |
| 14 | 171715050 |
| 15 | 843004688 |
| 16 | 4110478470 |
| 17 | 19950471120 |
| 18 | 96525524140 |
| 19 | 466068873900 |
| 20 | 2247609721431 |
| 21 | 10832163963860 |
| 22 | 52194011649150 |
| 23 | 251522234238000 |
| 24 | 1212501695554920 |
| 25 | 5848043487355752 |
| 26 | 28223528190496380 |
| 27 | 136307124614215660 |
| 28 | 658800774340433025 |
| 29 | 3186621527711606940 |