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 | 7 |
| 3 | 23 |
| 4 | 55 |
| 5 | 119 |
| 6 | 247 |
| 7 | 503 |
| 8 | 1015 |
| 9 | 2039 |
| 10 | 4087 |
| 11 | 8183 |
| 12 | 16375 |
| 13 | 32759 |
| 14 | 65527 |
| 15 | 131063 |
| 16 | 262135 |
| 17 | 524279 |
| 18 | 1048567 |
| 19 | 2097143 |
| 20 | 4194295 |
| 21 | 8388599 |
| 22 | 16777207 |
| 23 | 33554423 |
| 24 | 67108855 |
| 25 | 134217719 |
| 26 | 268435447 |
| 27 | 536870903 |
| 28 | 1073741815 |
| 29 | 2147483639 |
| 30 | 4294967287 |
| 31 | 8589934583 |
| 32 | 17179869175 |
| 33 | 34359738359 |