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) |
|---|---|
| 0 | 3 |
| 1 | 3 |
| 2 | 4 |
| 3 | 9 |
| 4 | 21 |
| 5 | 44 |
| 6 | 87 |
| 7 | 171 |
| 8 | 340 |
| 9 | 681 |
| 10 | 1365 |
| 11 | 2732 |
| 12 | 5463 |
| 13 | 10923 |
| 14 | 21844 |
| 15 | 43689 |
| 16 | 87381 |
| 17 | 174764 |
| 18 | 349527 |
| 19 | 699051 |
| 20 | 1398100 |
| 21 | 2796201 |
| 22 | 5592405 |
| 23 | 11184812 |
| 24 | 22369623 |
| 25 | 44739243 |
| 26 | 89478484 |
| 27 | 178956969 |
| 28 | 357913941 |
| 29 | 715827884 |
| 30 | 1431655767 |
| 31 | 2863311531 |