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 | 0 |
| 3 | 3 |
| 4 | -5 |
| 5 | -18 |
| 6 | 113 |
| 7 | 35 |
| 8 | -3044 |
| 9 | 9755 |
| 10 | 87999 |
| 11 | -882894 |
| 12 | -1155935 |
| 13 | 69780087 |
| 14 | -292042360 |
| 15 | -5040306157 |
| 16 | 64613044147 |
| 17 | 197030202470 |
| 18 | -10570955773551 |
| 19 | 48865639709115 |
| 20 | 1470783141900676 |
| 21 | -21819085085811861 |
| 22 | -123330624543827305 |
| 23 | 6244177033369108298 |
| 24 | -28216305335425392575 |
| 25 | -1453926618188019546193 |