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 | 30 |
| 6 | 900 |
| 7 | 2800 |
| 8 | 32010 |
| 9 | 139080 |
| 10 | 1276170 |
| 11 | 2960940 |
| 12 | 41625330 |
| 13 | 75086430 |
| 14 | 801519500 |
| 15 | 3162262140 |
| 16 | 16463761470 |
| 17 | 42395689530 |
| 18 | 579164323020 |
| 19 | 983928850100 |
| 20 | 11241276012750 |
| 21 | 37913042832500 |