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 | 33 |
| 3 | 99 |
| 4 | 135 |
| 5 | 855 |
| 6 | 2295 |
| 7 | 19575 |
| 8 | 38745 |
| 9 | 63855 |
| 10 | 121485 |
| 11 | 371925 |
| 12 | 3870195 |
| 13 | 8109585 |
| 14 | 28306005 |
| 15 | 36340395 |
| 16 | 113215095 |
| 17 | 463084245 |
| 18 | 672363615 |
| 19 | 675916395 |
| 20 | 686574735 |
| 21 | 1208140395 |