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 | -95 |
| 5 | -599 |
| 6 | -2159 |
| 7 | -5879 |
| 8 | 1276801 |
| 9 | 14669425 |
| 10 | 90669601 |
| 11 | 402407281 |
| 12 | -136515598559 |
| 13 | -2275742812199 |
| 14 | -19922903656655 |
| 15 | -122565283331399 |
| 16 | 56538094207096321 |
| 17 | 1235380139032068961 |
| 18 | 13993348375743336001 |
| 19 | 110062069784059565665 |