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 | -2 |
| 1 | 1 |
| 2 | -6 |
| 3 | 16 |
| 4 | -62 |
| 5 | 225 |
| 6 | -842 |
| 7 | 3136 |
| 8 | -11706 |
| 9 | 43681 |
| 10 | -163022 |
| 11 | 608400 |
| 12 | -2270582 |
| 13 | 8473921 |
| 14 | -31625106 |
| 15 | 118026496 |
| 16 | -440480882 |
| 17 | 1643897025 |
| 18 | -6135107222 |
| 19 | 22896531856 |
| 20 | -85451020206 |
| 21 | 318907548961 |
| 22 | -1190179175642 |
| 23 | 4441809153600 |
| 24 | -16577057438762 |
| 25 | 61866420601441 |
| 26 | -230888624967006 |