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 | -1 |
| 3 | 5 |
| 4 | 7 |
| 5 | 21 |
| 6 | -94 |
| 7 | -117 |
| 8 | -404 |
| 9 | -840 |
| 10 | 3541 |
| 11 | 4536 |
| 12 | 14412 |
| 13 | 31313 |
| 14 | 72175 |
| 15 | -249424 |
| 16 | -262828 |
| 17 | -930639 |
| 18 | -1895460 |
| 19 | -4441316 |
| 20 | -8085972 |
| 21 | 24112570 |
| 22 | 26214408 |
| 23 | 87131883 |
| 24 | 180197979 |
| 25 | 411759028 |
| 26 | 748154122 |
| 27 | 1525043990 |
| 28 | -3554837744 |
| 29 | -3210408245 |
| 30 | -11955482059 |
| 31 | -23817949142 |
| 32 | -55221348072 |