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 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 30 |
| 5 | 105 |
| 6 | 369 |
| 7 | 1281 |
| 8 | 4380 |
| 9 | 14769 |
| 10 | 49215 |
| 11 | 162393 |
| 12 | 531450 |
| 13 | 1727193 |
| 14 | 5580141 |
| 15 | 17936145 |
| 16 | 57395640 |
| 17 | 182948577 |
| 18 | 581130747 |
| 19 | 1840247337 |
| 20 | 5811307350 |
| 21 | 18305618121 |
| 22 | 57531942633 |
| 23 | 180441092769 |
| 24 | 564859072980 |
| 25 | 1765184603025 |
| 26 | 5507375961399 |
| 27 | 17157594341241 |
| 28 | 53379182394930 |
| 29 | 165856745298489 |
| 30 | 514727830236645 |