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 | 1 |
| 3 | 0 |
| 4 | 2 |
| 5 | 2 |
| 6 | 5 |
| 7 | 6 |
| 8 | 23 |
| 9 | 45 |
| 10 | 138 |
| 11 | 347 |
| 12 | 1007 |
| 13 | 2751 |
| 14 | 7998 |
| 15 | 22638 |
| 16 | 65708 |
| 17 | 189505 |
| 18 | 551798 |
| 19 | 1606383 |
| 20 | 4697905 |