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 | -2 |
| 3 | 7 |
| 4 | -27 |
| 5 | 114 |
| 6 | -506 |
| 7 | 2322 |
| 8 | -10919 |
| 9 | 52316 |
| 10 | -254369 |
| 11 | 1251563 |
| 12 | -6218656 |
| 13 | 31153743 |
| 14 | -157167147 |
| 15 | 797682007 |
| 16 | -4069817562 |
| 17 | 20860266354 |
| 18 | -107358128720 |
| 19 | 554533772363 |
| 20 | -2873667741743 |
| 21 | 14935575580894 |
| 22 | -77833224795929 |
| 23 | 406595414780038 |
| 24 | -2128748177726089 |
| 25 | 11167899337858904 |