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 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | 4 |
| 4 | -16 |
| 5 | 40 |
| 6 | -88 |
| 7 | 184 |
| 8 | -400 |
| 9 | 544 |
| 10 | -784 |
| 11 | 2224 |
| 12 | -11536 |
| 13 | 18016 |
| 14 | -10240 |
| 15 | 16384 |
| 16 | -86560 |
| 17 | 203296 |
| 18 | -503296 |
| 19 | 896512 |
| 20 | -2329600 |
| 21 | 2795776 |
| 22 | -1942528 |
| 23 | 8805088 |
| 24 | -54906208 |
| 25 | 77129728 |
| 26 | -30207616 |
| 27 | 70521376 |
| 28 | -383472160 |
| 29 | 840798784 |
| 30 | -2278740544 |
| 31 | 3898507264 |
| 32 | -6881424448 |
| 33 | 8016635968 |
| 34 | -3284792320 |
| 35 | 28687532032 |
| 36 | -252678823936 |
| 37 | 359583387328 |
| 38 | -135598386880 |