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 | 1 |
| 5 | 2 |
| 6 | 8 |
| 7 | 29 |
| 8 | 138 |
| 9 | 774 |
| 10 | 5678 |
| 11 | 53324 |
| 12 | 622716 |
| 13 | 8604351 |
| 14 | 135344959 |
| 15 | 2363662004 |
| 16 | 45134533117 |
| 17 | 933058713014 |
| 18 | 20735549517852 |
| 19 | 492653820710746 |