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 | 0 |
| 3 | -1 |
| 4 | -8 |
| 5 | -19 |
| 6 | 64 |
| 7 | 1091 |
| 8 | 7680 |
| 9 | -1415 |
| 10 | -650752 |
| 11 | -8575865 |
| 12 | -35559424 |
| 13 | 857890021 |
| 14 | 21380186112 |
| 15 | 203548592651 |
| 16 | -1615715926016 |
| 17 | -95486152906639 |
| 18 | -1599622990659584 |
| 19 | -1397194164399601 |
| 20 | 657963431581974528 |
| 21 | 18168041375501245021 |
| 22 | 157453907927886725120 |
| 23 | -6059840564222790027821 |