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 | 0 |
| 3 | -3 |
| 4 | -9 |
| 5 | -36 |
| 6 | -123 |
| 7 | -450 |
| 8 | -1764 |
| 9 | -6690 |
| 10 | -26649 |
| 11 | -104112 |
| 12 | -421248 |
| 13 | -1688337 |
| 14 | -6888978 |
| 15 | -28063296 |
| 16 | -115459524 |
| 17 | -475617330 |
| 18 | -1970737233 |
| 19 | -8184006855 |
| 20 | -34118533647 |
| 21 | -142565353488 |
| 22 | -597406140090 |