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 | -1 |
| 4 | -8 |
| 5 | -45 |
| 6 | -221 |
| 7 | -1014 |
| 8 | -4472 |
| 9 | -19227 |
| 10 | -81224 |
| 11 | -338767 |
| 12 | -1399320 |
| 13 | -5736705 |
| 14 | -23377770 |
| 15 | -94804944 |
| 16 | -382930847 |
| 17 | -1541565610 |
| 18 | -6188513994 |
| 19 | -24784429501 |
| 20 | -99058333803 |
| 21 | -395227906723 |
| 22 | -1574536914951 |
| 23 | -6264614281978 |
| 24 | -24896955293210 |
| 25 | -98848880984490 |