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 | 42 |
| 3 | 102 |
| 4 | 360 |
| 5 | 1068 |
| 6 | 3288 |
| 7 | 9864 |
| 8 | 29472 |
| 9 | 87312 |
| 10 | 257184 |
| 11 | 753504 |
| 12 | 2197632 |
| 13 | 6383808 |
| 14 | 18478464 |
| 15 | 53318784 |
| 16 | 153414144 |
| 17 | 440293632 |
| 18 | 1260710400 |
| 19 | 3602253312 |
| 20 | 10273007616 |
| 21 | 29245172736 |
| 22 | 83119822848 |
| 23 | 235886217216 |
| 24 | 668491456512 |
| 25 | 1892026552320 |