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 | 1 |
| 4 | 0 |
| 5 | -4 |
| 6 | -14 |
| 7 | -34 |
| 8 | -34 |
| 9 | 190 |
| 10 | 1366 |
| 11 | 5446 |
| 12 | 11056 |
| 13 | -30744 |
| 14 | -421420 |
| 15 | -2403764 |
| 16 | -7434244 |
| 17 | 9782396 |
| 18 | 296347996 |
| 19 | 2257819420 |
| 20 | 9461601856 |
| 21 | -1690329584 |
| 22 | -395833164264 |
| 23 | -3872875071064 |
| 24 | -20629371958040 |
| 25 | -17208144880024 |
| 26 | 893208132927176 |
| 27 | 10962683317693576 |