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 | 3 |
| 4 | -2 |
| 5 | 11 |
| 6 | -29 |
| 7 | 21 |
| 8 | -305 |
| 9 | -764 |
| 10 | -3761 |
| 11 | -26829 |
| 12 | 20827 |
| 13 | -1044667 |
| 14 | 7336774 |
| 15 | -34981779 |
| 16 | 829881529 |
| 17 | 4656917815 |
| 18 | 116074261249 |
| 19 | 2133710863224 |
| 20 | 4261714316929 |
| 21 | 871401830149817 |
| 22 | -15861891538169783 |
| 23 | 387559539627947379 |
| 24 | -20207945101587735626 |
| 25 | -195471056819748264101 |