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 | 260 |
| 3 | 27420 |
| 4 | 2504560 |
| 5 | 223723080 |
| 6 | 19923617840 |
| 7 | 1773563554900 |
| 8 | 157870122686600 |
| 9 | 14052371971981100 |
| 10 | 1250831588811052320 |
| 11 | 111339169110472830220 |
| 12 | 9910535055491682625400 |
| 13 | 882157695038695625086700 |
| 14 | 78522722964255506997330800 |
| 15 | 6989473714324564174042717340 |