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 | 6 |
| 2 | 18 |
| 3 | 48 |
| 4 | 141 |
| 5 | 431 |
| 6 | 1427 |
| 7 | 4692 |
| 8 | 15417 |
| 9 | 52833 |
| 10 | 189576 |
| 11 | 667458 |
| 12 | 2303485 |
| 13 | 8261483 |
| 14 | 30854617 |
| 15 | 112235989 |
| 16 | 396544978 |
| 17 | 1457813051 |
| 18 | 5573491517 |
| 19 | 20668205325 |
| 20 | 74283571059 |
| 21 | 277368667214 |
| 22 | 1076038620556 |
| 23 | 4041473193751 |
| 24 | 14706699067814 |