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 | 4 |
| 2 | 9 |
| 3 | 15 |
| 4 | 21 |
| 5 | 33 |
| 6 | 38 |
| 7 | 58 |
| 8 | 65 |
| 9 | 86 |
| 10 | 106 |
| 11 | 121 |
| 12 | 129 |
| 13 | 265 |
| 14 | 511 |
| 15 | 2047 |
| 16 | 2049 |
| 17 | 4097 |
| 18 | 4109 |
| 19 | 8193 |
| 20 | 17855 |
| 21 | 19857 |
| 22 | 34709 |
| 23 | 66233 |
| 24 | 104739 |
| 25 | 130953 |
| 26 | 131209 |
| 27 | 140474 |
| 28 | 220918 |
| 29 | 258931 |
| 30 | 511673 |
| 31 | 540951 |