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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | -3 |
| 7 | 7 |
| 8 | -10 |
| 9 | -5 |
| 10 | 84 |
| 11 | -248 |
| 12 | 90 |
| 13 | 2160 |
| 14 | -7541 |
| 15 | -5846 |
| 16 | 122824 |
| 17 | -186259 |
| 18 | -2036532 |
| 19 | 8665409 |
| 20 | 36714511 |
| 21 | -345711246 |
| 22 | -517802065 |
| 23 | 14415153844 |
| 24 | -9423161197 |
| 25 | -653074772917 |
| 26 | 1896978939457 |
| 27 | 32374651932128 |
| 28 | -184814895196023 |
| 29 | -1733326272860598 |
| 30 | 16839263882542991 |
| 31 | 96742403684106435 |