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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 4 |
| 7 | 14 |
| 8 | 60 |
| 9 | 210 |
| 10 | 728 |
| 11 | 2442 |
| 12 | 8252 |
| 13 | 27716 |
| 14 | 93924 |
| 15 | 319964 |
| 16 | 1098900 |
| 17 | 3800928 |
| 18 | 13244836 |
| 19 | 46460738 |
| 20 | 164015272 |
| 21 | 582353976 |
| 22 | 2078812492 |
| 23 | 7457141650 |
| 24 | 26871707908 |
| 25 | 97236327900 |
| 26 | 353213328024 |
| 27 | 1287648322950 |
| 28 | 4709765510884 |
| 29 | 17279999438748 |
| 30 | 63583033400968 |