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) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 21 |
| 3 | 225 |
| 4 | 3201 |
| 5 | 56913 |
| 6 | 1214361 |
| 7 | 30229545 |
| 8 | 860016801 |
| 9 | 27525472353 |
| 10 | 978858962601 |
| 11 | 38291126920665 |
| 12 | 1634047719138801 |
| 13 | 75542860973042193 |
| 14 | 3761030066169432441 |
| 15 | 200624240375801784585 |
| 16 | 11415336789685550907201 |
| 17 | 690117422445926970890433 |
| 18 | 44175435307592982599575881 |