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 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 21 |
| 4 | 85 |
| 5 | 341 |
| 6 | 1365 |
| 7 | 5461 |
| 8 | 21845 |
| 9 | 87381 |
| 10 | 349525 |
| 11 | 1398101 |
| 12 | 5592405 |
| 13 | 22369621 |
| 14 | 89478485 |
| 15 | 357913941 |
| 16 | 1431655765 |
| 17 | 5726623061 |
| 18 | 22906492245 |
| 19 | 91625968981 |
| 20 | 366503875925 |
| 21 | 1466015503701 |
| 22 | 5864062014805 |
| 23 | 23456248059221 |
| 24 | 93824992236885 |
| 25 | 375299968947541 |