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 | 2 |
| 6 | 0 |
| 7 | 18 |
| 8 | 66 |
| 9 | 382 |
| 10 | 1104 |
| 11 | 4138 |
| 12 | 15324 |
| 13 | 61644 |
| 14 | 325456 |
| 15 | 2320948 |
| 16 | 17660110 |
| 17 | 148271962 |
| 18 | 1171109228 |
| 19 | 9257051746 |