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 | 3 |
| 5 | 25 |
| 6 | 145 |
| 7 | 756 |
| 8 | 3892 |
| 9 | 20644 |
| 10 | 114961 |
| 11 | 676533 |
| 12 | 4209513 |
| 13 | 27636258 |
| 14 | 190882952 |
| 15 | 1382925792 |
| 16 | 10480076627 |
| 17 | 82864738749 |
| 18 | 682076544033 |
| 19 | 5832741680788 |
| 20 | 51724157186816 |
| 21 | 474869814059620 |
| 22 | 4506715734253041 |
| 23 | 44152005846695761 |
| 24 | 445958869278028097 |