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 | 1 |
| 6 | 7 |
| 7 | 30 |
| 8 | 124 |
| 9 | 507 |
| 10 | 2036 |
| 11 | 8216 |
| 12 | 33515 |
| 13 | 138557 |
| 14 | 583040 |
| 15 | 2503093 |
| 16 | 10985364 |
| 17 | 49361893 |
| 18 | 227342301 |
| 19 | 1073896332 |
| 20 | 5204340846 |
| 21 | 25874724616 |
| 22 | 131937166616 |
| 23 | 689653979583 |
| 24 | 3693193801069 |
| 25 | 20247844510508 |
| 26 | 113564665880028 |
| 27 | 651138092719098 |
| 28 | 3813739129140469 |