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 | 1 |
| 1 | 9 |
| 2 | 25 |
| 3 | 57 |
| 4 | 121 |
| 5 | 249 |
| 6 | 505 |
| 7 | 1017 |
| 8 | 2041 |
| 9 | 4089 |
| 10 | 8185 |
| 11 | 16377 |
| 12 | 32761 |
| 13 | 65529 |
| 14 | 131065 |
| 15 | 262137 |
| 16 | 524281 |
| 17 | 1048569 |
| 18 | 2097145 |
| 19 | 4194297 |
| 20 | 8388601 |
| 21 | 16777209 |
| 22 | 33554425 |
| 23 | 67108857 |
| 24 | 134217721 |
| 25 | 268435449 |
| 26 | 536870905 |
| 27 | 1073741817 |
| 28 | 2147483641 |
| 29 | 4294967289 |
| 30 | 8589934585 |