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 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 90 |
| 5 | 2025 |
| 6 | 102060 |
| 7 | 11573604 |
| 8 | 2946308904 |
| 9 | 1687603650084 |
| 10 | 2171945897658108 |
| 11 | 6289412333143466241 |
| 12 | 40940643700218614247324 |
| 13 | 599627833263501883888374756 |
| 14 | 19747212169938041691404746667280 |
| 15 | 1463229065460461810019231236067824400 |