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 | 1 |
| 2 | 1 |
| 3 | -2 |
| 4 | 5 |
| 5 | -14 |
| 6 | 40 |
| 7 | -111 |
| 8 | 293 |
| 9 | -731 |
| 10 | 1726 |
| 11 | -3882 |
| 12 | 8408 |
| 13 | -17796 |
| 14 | 37423 |
| 15 | -79337 |
| 16 | 170917 |
| 17 | -373812 |
| 18 | 823585 |
| 19 | -1809844 |
| 20 | 3934750 |
| 21 | -8424747 |
| 22 | 17749392 |
| 23 | -36874749 |
| 24 | 75862016 |
| 25 | -155359339 |
| 26 | 318331170 |
| 27 | -655146929 |
| 28 | 1356952623 |
| 29 | -2828151136 |
| 30 | 5920984735 |
| 31 | -12420140296 |
| 32 | 26036563525 |