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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 16 |
| 4 | 128 |
| 5 | 640 |
| 6 | 2560 |
| 7 | 8960 |
| 8 | 28672 |
| 9 | 86016 |
| 10 | 245760 |
| 11 | 675840 |
| 12 | 1802240 |
| 13 | 4685824 |
| 14 | 11927552 |
| 15 | 29818880 |
| 16 | 73400320 |
| 17 | 178257920 |
| 18 | 427819008 |
| 19 | 1016070144 |
| 20 | 2390753280 |
| 21 | 5578424320 |
| 22 | 12918456320 |
| 23 | 29712449536 |
| 24 | 67914170368 |
| 25 | 154350387200 |
| 26 | 348966092800 |
| 27 | 785173708800 |
| 28 | 1758789107712 |