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 | 5 |
| 3 | 17 |
| 4 | 81 |
| 5 | 257 |
| 6 | 1345 |
| 7 | 4097 |
| 8 | 20737 |
| 9 | 69633 |
| 10 | 328705 |
| 11 | 1048577 |
| 12 | 5574657 |
| 13 | 16777217 |
| 14 | 83902465 |
| 15 | 286261249 |
| 16 | 1359020033 |
| 17 | 4294967297 |
| 18 | 22565617665 |
| 19 | 68719476737 |
| 20 | 348967141377 |
| 21 | 1168499539969 |
| 22 | 5497562333185 |
| 23 | 17592186044417 |
| 24 | 93531519582209 |
| 25 | 282574488338433 |