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 | -4 |
| 2 | -40 |
| 3 | 672 |
| 4 | 8064 |
| 5 | -253440 |
| 6 | -3294720 |
| 7 | 153753600 |
| 8 | 2091048960 |
| 9 | -130025226240 |
| 10 | -1820353167360 |
| 11 | 141707492720640 |
| 12 | 2024392753152000 |
| 13 | -189483161695027200 |
| 14 | -2747505844577894400 |
| 15 | 300609462994993152000 |
| 16 | 4408938790593232896000 |