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 | 1 |
| 4 | -23 |
| 5 | -119 |
| 6 | -359 |
| 7 | -839 |
| 8 | 18481 |
| 9 | 178417 |
| 10 | 902161 |
| 11 | 3318481 |
| 12 | -69866279 |
| 13 | -1011908039 |
| 14 | -7204341143 |
| 15 | -36194591159 |
| 16 | 726745175521 |
| 17 | 14326789219681 |
| 18 | 131901636673441 |
| 19 | 840736509931297 |
| 20 | -16060449291985079 |
| 21 | -408041402342457239 |
| 22 | -4618341644958693959 |
| 23 | -35691963052019431079 |