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) |
|---|---|
| 3 | 4 |
| 4 | 36 |
| 5 | 224 |
| 6 | 1200 |
| 7 | 5940 |
| 8 | 28028 |
| 9 | 128128 |
| 10 | 572832 |
| 11 | 2519400 |
| 12 | 10943240 |
| 13 | 47070144 |
| 14 | 200880160 |
| 15 | 851809140 |
| 16 | 3592795500 |
| 17 | 15085939200 |
| 18 | 63102895680 |
| 19 | 263083395960 |
| 20 | 1093683448440 |
| 21 | 4535210472000 |
| 22 | 18764563053600 |
| 23 | 77485731403080 |
| 24 | 319402222692696 |
| 25 | 1314511549519104 |