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 | 3 |
| 2 | 21 |
| 3 | 129 |
| 4 | 777 |
| 5 | 4665 |
| 6 | 27993 |
| 7 | 167961 |
| 8 | 1007769 |
| 9 | 6046617 |
| 10 | 36279705 |
| 11 | 217678233 |
| 12 | 1306069401 |
| 13 | 7836416409 |
| 14 | 47018498457 |
| 15 | 282110990745 |
| 16 | 1692665944473 |
| 17 | 10155995666841 |
| 18 | 60935974001049 |
| 19 | 365615844006297 |
| 20 | 2193695064037785 |
| 21 | 13162170384226713 |
| 22 | 78973022305360281 |
| 23 | 473838133832161689 |