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 | 4 |
| 1 | 8 |
| 2 | 22 |
| 3 | 74 |
| 4 | 274 |
| 5 | 1058 |
| 6 | 4162 |
| 7 | 16514 |
| 8 | 65794 |
| 9 | 262658 |
| 10 | 1049602 |
| 11 | 4196354 |
| 12 | 16781314 |
| 13 | 67117058 |
| 14 | 268451842 |
| 15 | 1073774594 |
| 16 | 4295032834 |
| 17 | 17180000258 |
| 18 | 68719738882 |
| 19 | 274878431234 |
| 20 | 1099512676354 |
| 21 | 4398048608258 |
| 22 | 17592190238722 |
| 23 | 70368752566274 |
| 24 | 281474993487874 |
| 25 | 1125899940397058 |