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 | 13 |
| 4 | 147 |
| 5 | 1965 |
| 6 | 30979 |
| 7 | 559357 |
| 8 | 11289219 |
| 9 | 250794109 |
| 10 | 6066778627 |
| 11 | 158533572861 |
| 12 | 4447703062787 |
| 13 | 133309656009469 |
| 14 | 4251322261512195 |
| 15 | 143749952968507389 |
| 16 | 5137921526511802371 |
| 17 | 193589838004887201789 |
| 18 | 7670544451820808601603 |
| 19 | 318892867844484240154621 |
| 20 | 13881730766388536085356547 |