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 | -2 |
| 4 | -13 |
| 5 | 61 |
| 6 | 612 |
| 7 | -8924 |
| 8 | -41991 |
| 9 | 2821876 |
| 10 | -22689807 |
| 11 | -1196339088 |
| 12 | 45175812442 |
| 13 | 10968806278 |
| 14 | -63633205318330 |
| 15 | 2495113782094766 |
| 16 | 31372553334367367 |
| 17 | -8832192422722410665 |
| 18 | 421480840601004167822 |
| 19 | 9536361803340658184343 |