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 | 3 |
| 3 | 5 |
| 4 | 9 |
| 5 | 45 |
| 6 | 99 |
| 7 | 53559 |
| 8 | 1143357 |
| 9 | 2027985 |
| 10 | 36806085 |
| 11 | 1773607905 |
| 12 | 3314574181 |
| 13 | 1045463125509 |
| 14 | 1226640523999 |
| 15 | 3567404505159 |
| 16 | 28726885591099 |
| 17 | 39880799734039 |
| 18 | 87977068273719 |
| 19 | 106436400721299 |
| 20 | 339966033494859 |
| 21 | 999567363539883 |