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 | 1 |
| 1 | 3 |
| 2 | 15 |
| 3 | 120 |
| 4 | 1365 |
| 5 | 20349 |
| 6 | 376740 |
| 7 | 8347680 |
| 8 | 215553195 |
| 9 | 6358402050 |
| 10 | 210980549208 |
| 11 | 7778680504140 |
| 12 | 315502265971620 |
| 13 | 13961746143269400 |
| 14 | 669413654240461560 |
| 15 | 34569147570568156800 |
| 16 | 1912924003884628655655 |
| 17 | 112923282067713332728110 |