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) |
|---|---|
| 1 | 2 |
| 2 | 1 |
| 3 | -1 |
| 4 | 1 |
| 5 | -1 |
| 6 | 0 |
| 7 | 5 |
| 8 | -20 |
| 9 | 55 |
| 10 | -125 |
| 11 | 251 |
| 12 | -462 |
| 13 | 803 |
| 14 | -1364 |
| 15 | 2365 |
| 16 | -4367 |
| 17 | 8735 |
| 18 | -18564 |
| 19 | 40409 |
| 20 | -87380 |
| 21 | 184603 |
| 22 | -379049 |
| 23 | 758099 |
| 24 | -1486674 |
| 25 | 2884775 |
| 26 | -5592404 |
| 27 | 10919089 |
| 28 | -21572459 |
| 29 | 43144919 |
| 30 | -87087000 |
| 31 | 176565485 |
| 32 | -357913940 |
| 33 | 723002335 |
| 34 | -1453179125 |
| 35 | 2906358250 |