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 | 1 |
| 3 | 1 |
| 4 | 0 |
| 5 | -4 |
| 6 | -14 |
| 7 | -34 |
| 8 | 71 |
| 9 | 1135 |
| 10 | 6091 |
| 11 | 22771 |
| 12 | -87119 |
| 13 | -1847559 |
| 14 | -13769755 |
| 15 | -70046339 |
| 16 | 390688481 |
| 17 | 10473961121 |
| 18 | 100030347361 |
| 19 | 643972996705 |
| 20 | -4717305354419 |
| 21 | -153449916040259 |
| 22 | -1787926183752939 |
| 23 | -13926752488607419 |
| 24 | 126329848106764765 |