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 | -3 |
| 3 | 3 |
| 4 | 41 |
| 5 | 87 |
| 6 | -571 |
| 7 | -5701 |
| 8 | -14575 |
| 9 | 156655 |
| 10 | 2094925 |
| 11 | 9148851 |
| 12 | -63364423 |
| 13 | -1474212665 |
| 14 | -11494853995 |
| 15 | 10945362411 |
| 16 | 1520718442785 |
| 17 | 20719421344991 |
| 18 | 100137575499165 |
| 19 | -1638818071763869 |
| 20 | -45333849658449847 |
| 21 | -512404024891840969 |
| 22 | -577060092568365467 |
| 23 | 99142586163648127771 |