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 | 1 |
| 2 | 3 |
| 3 | 15 |
| 4 | 108 |
| 5 | 1036 |
| 6 | 12569 |
| 7 | 185704 |
| 8 | 3247546 |
| 9 | 65762269 |
| 10 | 1515642725 |
| 11 | 39211570981 |
| 12 | 1125987938801 |
| 13 | 35554753133312 |
| 14 | 1224882431140838 |
| 15 | 45731901253649898 |
| 16 | 1839804317195739634 |
| 17 | 79355626796692509253 |
| 18 | 3653687500034925338348 |