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 | -3 |
| 2 | 0 |
| 3 | -4 |
| 4 | -21 |
| 5 | -129 |
| 6 | -910 |
| 7 | -7242 |
| 8 | -64155 |
| 9 | -626319 |
| 10 | -6685548 |
| 11 | -77527104 |
| 12 | -971315713 |
| 13 | -13084909917 |
| 14 | -188723009274 |
| 15 | -2902997766470 |
| 16 | -47458671376503 |
| 17 | -821951603042523 |
| 18 | -15037432614035864 |
| 19 | -289828080356525052 |
| 20 | -5870642802374608509 |
| 21 | -124691017072423632777 |