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 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 11 |
| 6 | 25 |
| 7 | 127 |
| 8 | 441 |
| 9 | 1954 |
| 10 | 10011 |
| 11 | 45266 |
| 12 | 264583 |
| 13 | 1445380 |
| 14 | 8585655 |
| 15 | 55660801 |
| 16 | 352151073 |
| 17 | 2482766225 |
| 18 | 17559191557 |
| 19 | 129772490863 |
| 20 | 1013321885751 |
| 21 | 7972553309386 |
| 22 | 66428256850935 |
| 23 | 564371629663172 |
| 24 | 4946383948336009 |
| 25 | 45027627776367801 |
| 26 | 416996057365437135 |