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 | 1 |
| 5 | -599 |
| 6 | -4319 |
| 7 | -17639 |
| 8 | -53759 |
| 9 | -136079 |
| 10 | 181137601 |
| 11 | 2414356561 |
| 12 | 17242917121 |
| 13 | 87695201881 |
| 14 | 355974659041 |
| 15 | -734340892685399 |
| 16 | -14279571631503359 |
| 17 | -145614163414530719 |
| 18 | -1037158816523518079 |
| 19 | -5794132157196668639 |
| 20 | 16192314610730781350401 |