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 | 3 |
| 2 | 21 |
| 3 | 21 |
| 4 | 21 |
| 5 | 675 |
| 6 | 4725 |
| 7 | 4725 |
| 8 | 98175 |
| 9 | 140175 |
| 10 | 543375 |
| 11 | 543375 |
| 12 | 23186625 |
| 13 | 35026425 |
| 14 | 139264125 |
| 15 | 139264125 |
| 16 | 608679225 |
| 17 | 11553990525 |
| 18 | 87662479905 |
| 19 | 87662479905 |
| 20 | 343947649815 |
| 21 | 2383529269275 |
| 22 | 4005262262925 |
| 23 | 4005262262925 |