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 | 4 |
| 1 | -2 |
| 2 | 1 |
| 3 | 7 |
| 4 | -11 |
| 5 | 43 |
| 6 | -59 |
| 7 | 187 |
| 8 | -251 |
| 9 | 763 |
| 10 | -1019 |
| 11 | 3067 |
| 12 | -4091 |
| 13 | 12283 |
| 14 | -16379 |
| 15 | 49147 |
| 16 | -65531 |
| 17 | 196603 |
| 18 | -262139 |
| 19 | 786427 |
| 20 | -1048571 |
| 21 | 3145723 |
| 22 | -4194299 |
| 23 | 12582907 |
| 24 | -16777211 |
| 25 | 50331643 |
| 26 | -67108859 |
| 27 | 201326587 |
| 28 | -268435451 |
| 29 | 805306363 |
| 30 | -1073741819 |
| 31 | 3221225467 |