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 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 1 |
| 7 | 3 |
| 8 | 7 |
| 9 | 21 |
| 10 | 60 |
| 11 | 168 |
| 12 | 472 |
| 13 | 1344 |
| 14 | 3843 |
| 15 | 11104 |
| 16 | 32305 |
| 17 | 94734 |
| 18 | 279708 |
| 19 | 831401 |
| 20 | 2485877 |
| 21 | 7474667 |
| 22 | 22589771 |
| 23 | 68594611 |
| 24 | 209198103 |
| 25 | 640591332 |
| 26 | 1968920180 |
| 27 | 6072766832 |
| 28 | 18791062733 |
| 29 | 58321579888 |
| 30 | 181524367875 |
| 31 | 566488767763 |
| 32 | 1772261945866 |
| 33 | 5557515157647 |