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 | -3 |
| 3 | -6 |
| 4 | -18 |
| 5 | -27 |
| 6 | -108 |
| 7 | -81 |
| 8 | -486 |
| 9 | 0 |
| 10 | -1458 |
| 11 | 8748 |
| 12 | -6561 |
| 13 | 118098 |
| 14 | 118098 |
| 15 | 1003833 |
| 16 | 1417176 |
| 17 | 11691702 |
| 18 | 9565938 |
| 19 | 105225318 |
| 20 | 114791256 |
| 21 | 746143164 |
| 22 | 1076168025 |
| 23 | 7231849128 |
| 24 | 2324522934 |
| 25 | 58113073350 |
| 26 | 45328197213 |
| 27 | 334731302496 |
| 28 | 146444944842 |
| 29 | 3263630199336 |
| 30 | -3012581722464 |