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 | 18 |
| 4 | 54 |
| 5 | 108 |
| 6 | 324 |
| 7 | 648 |
| 8 | 1944 |
| 9 | 3888 |
| 10 | 11664 |
| 11 | 23328 |
| 12 | 69984 |
| 13 | 139968 |
| 14 | 419904 |
| 15 | 839808 |
| 16 | 2519424 |
| 17 | 5038848 |
| 18 | 15116544 |
| 19 | 30233088 |
| 20 | 90699264 |
| 21 | 181398528 |
| 22 | 544195584 |
| 23 | 1088391168 |
| 24 | 3265173504 |
| 25 | 6530347008 |
| 26 | 19591041024 |
| 27 | 39182082048 |