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) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 8 |
| 3 | 72 |
| 4 | 684 |
| 5 | 6876 |
| 6 | 72924 |
| 7 | 814056 |
| 8 | 9544164 |
| 9 | 117284766 |
| 10 | 1507813722 |
| 11 | 20243939784 |
| 12 | 283383218358 |
| 13 | 4129738188546 |
| 14 | 62563457162916 |
| 15 | 983985264479016 |
| 16 | 16046556350152008 |
| 17 | 271012423865891076 |
| 18 | 4735104984115971090 |
| 19 | 85496795448023574282 |
| 20 | 1593757450233067980306 |