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 | 16 |
| 4 | -115 |
| 5 | 996 |
| 6 | -9870 |
| 7 | 108816 |
| 8 | -1312227 |
| 9 | 17116900 |
| 10 | -239641798 |
| 11 | 3580451040 |
| 12 | -56837970358 |
| 13 | 955277226736 |
| 14 | -16948413979080 |
| 15 | 316615678469856 |
| 16 | -6213840704926947 |
| 17 | 127857371413743540 |
| 18 | -2753054722318717950 |