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 | 5 |
| 2 | 19 |
| 3 | 75 |
| 4 | 295 |
| 5 | 1161 |
| 6 | 4569 |
| 7 | 17981 |
| 8 | 70763 |
| 9 | 278483 |
| 10 | 1095951 |
| 11 | 4313041 |
| 12 | 16973681 |
| 13 | 66798773 |
| 14 | 262882051 |
| 15 | 1034554523 |
| 16 | 4071419319 |
| 17 | 16022795225 |
| 18 | 63056626377 |
| 19 | 248155086189 |
| 20 | 976597549531 |
| 21 | 3843333571747 |
| 22 | 15125179200799 |
| 23 | 59524119253665 |