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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 20 |
| 7 | 70 |
| 8 | 182 |
| 9 | 420 |
| 10 | 912 |
| 11 | 1914 |
| 12 | 3938 |
| 13 | 8008 |
| 14 | 16172 |
| 15 | 32526 |
| 16 | 65262 |
| 17 | 130764 |
| 18 | 261800 |
| 19 | 523906 |
| 20 | 1048154 |
| 21 | 2096688 |
| 22 | 4193796 |
| 23 | 8388054 |
| 24 | 16776614 |
| 25 | 33553780 |
| 26 | 67108160 |
| 27 | 134216970 |