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 | 4 |
| 3 | -7 |
| 4 | 18 |
| 5 | -38 |
| 6 | 88 |
| 7 | -195 |
| 8 | 441 |
| 9 | -988 |
| 10 | 2223 |
| 11 | -4992 |
| 12 | 11220 |
| 13 | -25208 |
| 14 | 56645 |
| 15 | -127277 |
| 16 | 285992 |
| 17 | -642615 |
| 18 | 1443946 |
| 19 | -3244514 |
| 20 | 7290360 |
| 21 | -16381287 |
| 22 | 36808421 |
| 23 | -82707768 |
| 24 | 185842671 |
| 25 | -417584688 |
| 26 | 938304280 |
| 27 | -2108350576 |
| 28 | 4737420745 |
| 29 | -10644887785 |
| 30 | 23918845740 |
| 31 | -53745158519 |
| 32 | 120764274994 |