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 | 5 |
| 3 | 221 |
| 4 | 1513 |
| 5 | 71065 |
| 6 | 487085 |
| 7 | 22882613 |
| 8 | 156839761 |
| 9 | 7368130225 |
| 10 | 50501915861 |
| 11 | 2372515049741 |
| 12 | 16261460067385 |
| 13 | 763942477886281 |
| 14 | 5236139639782013 |
| 15 | 245987105364332645 |
| 16 | 1686020702549740705 |
| 17 | 79207083984837225313 |
| 18 | 542893430081376724901 |
| 19 | 25504435056012222218045 |