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 | 13 |
| 2 | 37 |
| 3 | 181 |
| 4 | 373 |
| 5 | 757 |
| 6 | 3061 |
| 7 | 6133 |
| 8 | 12277 |
| 9 | 196597 |
| 10 | 1572853 |
| 11 | 25165813 |
| 12 | 805306357 |
| 13 | 3221225461 |
| 14 | 6442450933 |
| 15 | 12884901877 |
| 16 | 26388279066613 |
| 17 | 3377699720527861 |
| 18 | 1813388729421943762059253 |