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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 13 |
| 5 | 121 |
| 6 | 1081 |
| 7 | 10081 |
| 8 | 100801 |
| 9 | 1088641 |
| 10 | 12700801 |
| 11 | 159667201 |
| 12 | 2155507201 |
| 13 | 31135104001 |
| 14 | 479480601601 |
| 15 | 7846046208001 |
| 16 | 135998134272001 |
| 17 | 2489811996672001 |
| 18 | 48017802792960001 |
| 19 | 973160803270656001 |
| 20 | 20679667069501440001 |
| 21 | 459818479545384960001 |
| 22 | 10678006913887272960001 |