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 | 4 |
| 6 | 22 |
| 7 | 80 |
| 8 | 304 |
| 9 | 1043 |
| 10 | 3538 |
| 11 | 12094 |
| 12 | 42979 |
| 13 | 156237 |
| 14 | 587926 |
| 15 | 2283038 |
| 16 | 9142910 |
| 17 | 37708601 |
| 18 | 160014979 |
| 19 | 697523776 |
| 20 | 3119511496 |
| 21 | 14295524835 |
| 22 | 67052144163 |
| 23 | 321571055089 |
| 24 | 1575370699764 |
| 25 | 7876854373196 |
| 26 | 40164235356266 |
| 27 | 208699490940770 |