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 | 1 |
| 3 | 3 |
| 4 | 20 |
| 5 | 260 |
| 6 | 6304 |
| 7 | 281096 |
| 8 | 23095768 |
| 9 | 3534364152 |
| 10 | 1022066008944 |
| 11 | 566769639800624 |
| 12 | 610404514456781600 |
| 13 | 1289451019913455115232 |
| 14 | 5380706591109919979010304 |
| 15 | 44564091018102742571511384320 |
| 16 | 734792950974385564221797653105152 |