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 | 0 |
| 2 | 4 |
| 3 | 12 |
| 4 | 128 |
| 5 | 1040 |
| 6 | 12672 |
| 7 | 161728 |
| 8 | 2481152 |
| 9 | 41806080 |
| 10 | 791613440 |
| 11 | 16399944704 |
| 12 | 371591995392 |
| 13 | 9110211874816 |
| 14 | 240670782291968 |
| 15 | 6810264853463040 |
| 16 | 205583847590985728 |
| 17 | 6593508525460226048 |
| 18 | 223913466256013918208 |
| 19 | 8026367531323488993280 |