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 | -9 |
| 2 | 27 |
| 3 | -18 |
| 4 | -351 |
| 5 | 1080 |
| 6 | 216 |
| 7 | -5850 |
| 8 | 9639 |
| 9 | -306 |
| 10 | -35640 |
| 11 | 96120 |
| 12 | -16848 |
| 13 | -356490 |
| 14 | 508950 |
| 15 | 131760 |
| 16 | -1821015 |
| 17 | 4139424 |
| 18 | 69768 |
| 19 | -13621698 |
| 20 | 18996120 |
| 21 | -4925700 |
| 22 | -57383640 |
| 23 | 136178064 |
| 24 | 21282912 |
| 25 | -405810225 |
| 26 | 557193870 |
| 27 | -1767762 |
| 28 | -1859194350 |
| 29 | 3887571240 |
| 30 | -539161920 |