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 | 63 |
| 5 | 159 |
| 6 | 383 |
| 7 | 895 |
| 8 | 2047 |
| 9 | 4607 |
| 10 | 10239 |
| 11 | 22527 |
| 12 | 49151 |
| 13 | 106495 |
| 14 | 229375 |
| 15 | 491519 |
| 16 | 1048575 |
| 17 | 2228223 |
| 18 | 4718591 |
| 19 | 9961471 |
| 20 | 20971519 |
| 21 | 44040191 |
| 22 | 92274687 |
| 23 | 192937983 |
| 24 | 402653183 |
| 25 | 838860799 |
| 26 | 1744830463 |
| 27 | 3623878655 |
| 28 | 7516192767 |
| 29 | 15569256447 |
| 30 | 32212254719 |
| 31 | 66571993087 |