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 | 1 |
| 4 | -11 |
| 5 | 61 |
| 6 | 301 |
| 7 | -6299 |
| 8 | 7561 |
| 9 | 903673 |
| 10 | -9019079 |
| 11 | -145636919 |
| 12 | 4305630781 |
| 13 | 7516191541 |
| 14 | -2037845181371 |
| 15 | 22442805921901 |
| 16 | 944219385367441 |
| 17 | -29922880660473359 |
| 18 | -288352494154313999 |
| 19 | 32071808922904896913 |
| 20 | -273044292430852251899 |