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 | 9 |
| 3 | 129 |
| 4 | 47169 |
| 5 | 1049913 |
| 6 | 615504609 |
| 7 | 15797864577 |
| 8 | 11270258161281 |
| 9 | 246696657053411097 |
| 10 | 7087786816380876801 |
| 11 | 178199489594187990894537 |
| 12 | 158945391097530669380671857 |
| 13 | 4791412124651983778003371329 |