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 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 36 |
| 5 | 225 |
| 6 | 1350 |
| 7 | 11025 |
| 8 | 88200 |
| 9 | 893025 |
| 10 | 8930250 |
| 11 | 108056025 |
| 12 | 1296672300 |
| 13 | 18261468225 |
| 14 | 255660555150 |
| 15 | 4108830350625 |
| 16 | 65741285610000 |
| 17 | 1187451971330625 |
| 18 | 21374135483951250 |
| 19 | 428670161650355625 |
| 20 | 8573403233007112500 |