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 | 144 |
| 4 | 432 |
| 5 | 1098 |
| 6 | 3150 |
| 7 | 8244 |
| 8 | 23202 |
| 9 | 61560 |
| 10 | 171468 |
| 11 | 458640 |
| 12 | 1269144 |
| 13 | 3412944 |
| 14 | 9402156 |
| 15 | 25378560 |
| 16 | 69694632 |
| 17 | 188620632 |
| 18 | 516830904 |
| 19 | 1401394608 |
| 20 | 3833746488 |
| 21 | 10409369472 |
| 22 | 28443841344 |
| 23 | 77305743936 |
| 24 | 211065666624 |
| 25 | 574042728672 |