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) |
|---|---|
| 4 | 7 |
| 5 | 31 |
| 6 | 181 |
| 7 | 1261 |
| 8 | 10081 |
| 9 | 90721 |
| 10 | 907201 |
| 11 | 9979201 |
| 12 | 119750401 |
| 13 | 1556755201 |
| 14 | 21794572801 |
| 15 | 326918592001 |
| 16 | 5230697472001 |
| 17 | 88921857024001 |
| 18 | 1600593426432001 |
| 19 | 30411275102208001 |
| 20 | 608225502044160001 |
| 21 | 12772735542927360001 |