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 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 3600 |
| 7 | 2882737 |
| 8 | 229095676 |
| 9 | 6655170642 |
| 10 | 103395053720 |
| 11 | 1051588999820 |
| 12 | 7878155295948 |
| 13 | 46838274976147 |
| 14 | 232322652402464 |
| 15 | 995789500001315 |
| 16 | 3784235129731708 |
| 17 | 12999197522073908 |
| 18 | 40969826999523768 |
| 19 | 119876498636101786 |
| 20 | 328726265508168780 |
| 21 | 851369417500529061 |