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 | 8 |
| 4 | -17 |
| 5 | -1 |
| 6 | 116 |
| 7 | -344 |
| 8 | 239 |
| 9 | 1709 |
| 10 | -7001 |
| 11 | 9316 |
| 12 | 22276 |
| 13 | -138412 |
| 14 | 268568 |
| 15 | 189008 |
| 16 | -2608913 |
| 17 | 6809417 |
| 18 | -1814851 |
| 19 | -45852416 |
| 20 | 159116983 |
| 21 | -155628353 |
| 22 | -720492928 |
| 23 | 3481793888 |
| 24 | -5558713852 |
| 25 | -9029921876 |
| 26 | 71541001076 |
| 27 | -158672882224 |
| 28 | -45300345128 |
| 29 | 1370202238072 |