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 | 4 |
| 4 | 12 |
| 5 | 40 |
| 6 | 128 |
| 7 | 402 |
| 8 | 1278 |
| 9 | 4040 |
| 10 | 12776 |
| 11 | 40417 |
| 12 | 127803 |
| 13 | 404136 |
| 14 | 1277995 |
| 15 | 4041401 |
| 16 | 12779996 |
| 17 | 40413886 |
| 18 | 127799963 |