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 | 28 |
| 4 | 84 |
| 5 | 255 |
| 6 | 772 |
| 7 | 2340 |
| 8 | 7088 |
| 9 | 21476 |
| 10 | 65064 |
| 11 | 197126 |
| 12 | 597228 |
| 13 | 1809420 |
| 14 | 5481980 |
| 15 | 16608712 |
| 16 | 50319264 |
| 17 | 152451844 |
| 18 | 461882016 |
| 19 | 1399359936 |
| 20 | 4239628608 |
| 21 | 12844765920 |
| 22 | 38915675520 |
| 23 | 117902483528 |
| 24 | 357208128400 |
| 25 | 1082230358448 |
| 26 | 3278823900048 |
| 27 | 9933824239744 |