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 | 0 |
| 1 | 3 |
| 2 | -5 |
| 3 | 9 |
| 4 | -16 |
| 5 | 30 |
| 6 | -63 |
| 7 | 129 |
| 8 | -257 |
| 9 | 513 |
| 10 | -1024 |
| 11 | 2046 |
| 12 | -4095 |
| 13 | 8193 |
| 14 | -16385 |
| 15 | 32769 |
| 16 | -65536 |
| 17 | 131070 |
| 18 | -262143 |
| 19 | 524289 |
| 20 | -1048577 |
| 21 | 2097153 |
| 22 | -4194304 |
| 23 | 8388606 |
| 24 | -16777215 |
| 25 | 33554433 |
| 26 | -67108865 |
| 27 | 134217729 |
| 28 | -268435456 |
| 29 | 536870910 |
| 30 | -1073741823 |
| 31 | 2147483649 |
| 32 | -4294967297 |
| 33 | 8589934593 |