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 | 4 |
| 3 | 7 |
| 4 | 7 |
| 5 | -18 |
| 6 | -152 |
| 7 | -648 |
| 8 | -2076 |
| 9 | -5006 |
| 10 | -6442 |
| 11 | 17866 |
| 12 | 178102 |
| 13 | 851516 |
| 14 | 3004912 |
| 15 | 7956103 |
| 16 | 11925503 |
| 17 | -24636636 |
| 18 | -298702394 |
| 19 | -1532903353 |
| 20 | -5722053149 |
| 21 | -16080843014 |
| 22 | -27090920172 |
| 23 | 37370086052 |
| 24 | 584086176148 |
| 25 | 3182365757908 |
| 26 | 12407797520932 |
| 27 | 36551266481968 |