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 | -5 |
| 3 | -10 |
| 4 | 73 |
| 5 | 1004 |
| 6 | 5473 |
| 7 | -15562 |
| 8 | -746447 |
| 9 | -9174088 |
| 10 | -41916959 |
| 11 | 823985546 |
| 12 | 24629093641 |
| 13 | 335144105828 |
| 14 | 1248594602305 |
| 15 | -67564407472426 |
| 16 | -2160461588461343 |
| 17 | -34957074099518608 |
| 18 | -154556217713939903 |
| 19 | 10500560586914149250 |
| 20 | 409146670525578079801 |