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 | 13 |
| 1 | 49 |
| 2 | 217 |
| 3 | 937 |
| 4 | 3913 |
| 5 | 16009 |
| 6 | 64777 |
| 7 | 260617 |
| 8 | 1045513 |
| 9 | 4188169 |
| 10 | 16764937 |
| 11 | 67084297 |
| 12 | 268386313 |
| 13 | 1073643529 |
| 14 | 4294770697 |
| 15 | 17179475977 |
| 16 | 68718690313 |
| 17 | 274876334089 |
| 18 | 1099508482057 |
| 19 | 4398040219657 |
| 20 | 17592173461513 |
| 21 | 70368719011849 |
| 22 | 281474926379017 |
| 23 | 1125899806179337 |
| 24 | 4503599426043913 |
| 25 | 18014398106828809 |