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 | 5 |
| 3 | -11 |
| 4 | 33 |
| 5 | -87 |
| 6 | 241 |
| 7 | -655 |
| 8 | 1793 |
| 9 | -4895 |
| 10 | 13377 |
| 11 | -36543 |
| 12 | 99841 |
| 13 | -272767 |
| 14 | 745217 |
| 15 | -2035967 |
| 16 | 5562369 |
| 17 | -15196671 |
| 18 | 41518081 |
| 19 | -113429503 |
| 20 | 309895169 |
| 21 | -846649343 |
| 22 | 2313089025 |
| 23 | -6319476735 |
| 24 | 17265131521 |
| 25 | -47169216511 |
| 26 | 128868696065 |
| 27 | -352075825151 |
| 28 | 961889042433 |
| 29 | -2627929735167 |