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 | -4 |
| 3 | 36 |
| 4 | -532 |
| 5 | 11040 |
| 6 | -295188 |
| 7 | 9655772 |
| 8 | -373422320 |
| 9 | 16666348464 |
| 10 | -843095987520 |
| 11 | 47669276120928 |
| 12 | -2979044176833888 |
| 13 | 203906085094788960 |
| 14 | -15170476121142482112 |
| 15 | 1218972837861962011200 |
| 16 | -105202043767190506428672 |
| 17 | 9705514148732971389369600 |