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) |
|---|---|
| 2 | 1 |
| 3 | 4 |
| 4 | 15 |
| 5 | 50 |
| 6 | 162 |
| 7 | 506 |
| 8 | 1558 |
| 9 | 4727 |
| 10 | 14227 |
| 11 | 42521 |
| 12 | 126506 |
| 13 | 374969 |
| 14 | 1108476 |
| 15 | 3269902 |
| 16 | 9630631 |
| 17 | 28328999 |
| 18 | 83251569 |
| 19 | 244471484 |
| 20 | 717486860 |
| 21 | 2104777227 |
| 22 | 6172357873 |
| 23 | 18096097750 |
| 24 | 53044095421 |
| 25 | 155464365080 |
| 26 | 455601800970 |
| 27 | 1335107222743 |
| 28 | 3912330438784 |
| 29 | 11464463809180 |
| 30 | 33595343643160 |