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) |
|---|---|
| 1 | 9 |
| 2 | 81 |
| 3 | 189 |
| 4 | 927 |
| 5 | 2889 |
| 6 | 11727 |
| 7 | 40581 |
| 8 | 154359 |
| 9 | 554733 |
| 10 | 2062215 |
| 11 | 7512453 |
| 12 | 27700479 |
| 13 | 101402109 |
| 14 | 372809655 |
| 15 | 1367107173 |
| 16 | 5021003151 |
| 17 | 18423673101 |
| 18 | 67639822407 |
| 19 | 248247487989 |
| 20 | 911283026751 |
| 21 | 3344800820445 |
| 22 | 12277727839863 |
| 23 | 45065827217925 |