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 | 5 |
| 3 | 29 |
| 4 | 218 |
| 5 | 1814 |
| 6 | 18144 |
| 7 | 196356 |
| 8 | 2427312 |
| 9 | 32304240 |
| 10 | 475637760 |
| 11 | 7460546400 |
| 12 | 127525829760 |
| 13 | 2302819079040 |
| 14 | 44659367020800 |
| 15 | 911770840108800 |
| 16 | 19784985947596800 |
| 17 | 449672462639769600 |
| 18 | 10790180876185804800 |
| 19 | 270071861749240320000 |
| 20 | 7094011359005190144000 |