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 | 3 |
| 2 | 9 |
| 3 | 27 |
| 4 | 81 |
| 5 | 243 |
| 6 | 540 |
| 7 | 1440 |
| 8 | 3804 |
| 9 | 9960 |
| 10 | 25908 |
| 11 | 67344 |
| 12 | 175884 |
| 13 | 458832 |
| 14 | 1196364 |
| 15 | 3119304 |
| 16 | 8134164 |
| 17 | 21212832 |
| 18 | 55316892 |
| 19 | 144249168 |
| 20 | 376159644 |
| 21 | 980918904 |
| 22 | 2557958964 |
| 23 | 6670420704 |
| 24 | 17394543180 |
| 25 | 45359994336 |
| 26 | 118285895244 |
| 27 | 308455762488 |
| 28 | 804364332180 |
| 29 | 2097551985168 |
| 30 | 5469815336796 |
| 31 | 14263713072192 |