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 | 1 |
| 2 | 2 |
| 3 | 0 |
| 4 | -24 |
| 5 | -148 |
| 6 | -248 |
| 7 | 5488 |
| 8 | 73024 |
| 9 | 346768 |
| 10 | -3749728 |
| 11 | -100273536 |
| 12 | -922745472 |
| 13 | 4147334336 |
| 14 | 283697686144 |
| 15 | 4362058183936 |
| 16 | 4465927211008 |
| 17 | -1382047649378048 |
| 18 | -33554250522144256 |
| 19 | -226963355560685568 |
| 20 | 10084981854738991104 |