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 | 2 |
| 2 | -3 |
| 3 | 22 |
| 4 | -103 |
| 5 | 522 |
| 6 | -2603 |
| 7 | 13022 |
| 8 | -65103 |
| 9 | 325522 |
| 10 | -1627603 |
| 11 | 8138022 |
| 12 | -40690103 |
| 13 | 203450522 |
| 14 | -1017252603 |
| 15 | 5086263022 |
| 16 | -25431315103 |
| 17 | 127156575522 |
| 18 | -635782877603 |
| 19 | 3178914388022 |
| 20 | -15894571940103 |
| 21 | 79472859700522 |