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 | 1 |
| 4 | 7 |
| 5 | 55 |
| 6 | 655 |
| 7 | 11147 |
| 8 | 287791 |
| 9 | 11787747 |
| 10 | 804475261 |
| 11 | 94875366649 |
| 12 | 19825870580671 |
| 13 | 7466490852631207 |
| 14 | 5129453728126116131 |
| 15 | 6487332587944013948099 |
| 16 | 15213161506747424007012971 |
| 17 | 66536415576917924594383104139 |
| 18 | 545371527333985035460963541248785 |