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 | 25 |
| 2 | 121 |
| 3 | 721 |
| 4 | 5041 |
| 5 | 40321 |
| 6 | 3628801 |
| 7 | 6227020801 |
| 8 | 87178291201 |
| 9 | 121645100408832001 |
| 10 | 2432902008176640001 |
| 11 | 620448401733239439360001 |
| 12 | 15511210043330985984000001 |
| 13 | 403291461126605635584000001 |
| 14 | 304888344611713860501504000001 |
| 15 | 295232799039604140847618609643520000001 |