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 | 3 |
| 2 | -9 |
| 3 | 20 |
| 4 | -46 |
| 5 | 103 |
| 6 | -232 |
| 7 | 521 |
| 8 | -1171 |
| 9 | 2631 |
| 10 | -5912 |
| 11 | 13284 |
| 12 | -29849 |
| 13 | 67070 |
| 14 | -150705 |
| 15 | 338631 |
| 16 | -760897 |
| 17 | 1709720 |
| 18 | -3841706 |
| 19 | 8632235 |
| 20 | -19396456 |
| 21 | 43583441 |
| 22 | -97931103 |
| 23 | 220049191 |
| 24 | -494446044 |
| 25 | 1111010176 |
| 26 | -2496417205 |
| 27 | 5609398542 |
| 28 | -12604204113 |
| 29 | 28321389563 |
| 30 | -63637584697 |