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 | 31 |
| 4 | 119 |
| 5 | 455 |
| 6 | 1799 |
| 7 | 7175 |
| 8 | 28679 |
| 9 | 114695 |
| 10 | 458759 |
| 11 | 1835015 |
| 12 | 7340039 |
| 13 | 29360135 |
| 14 | 117440519 |
| 15 | 469762055 |
| 16 | 1879048199 |
| 17 | 7516192775 |
| 18 | 30064771079 |
| 19 | 120259084295 |
| 20 | 481036337159 |
| 21 | 1924145348615 |
| 22 | 7696581394439 |
| 23 | 30786325577735 |
| 24 | 123145302310919 |
| 25 | 492581209243655 |