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 | 7 |
| 4 | 13 |
| 5 | 321 |
| 6 | 31 |
| 7 | 42673 |
| 8 | -214983 |
| 9 | 12251809 |
| 10 | -156239909 |
| 11 | 6366130761 |
| 12 | -135725103227 |
| 13 | 5265915854785 |
| 14 | -155145910919817 |
| 15 | 6318044844152161 |
| 16 | -232403136941014799 |
| 17 | 10299509100942804033 |
| 18 | -446889500139353805773 |
| 19 | 21789892230658085847673 |
| 20 | -1078684347590588362463619 |