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 | 1 |
| 2 | 6 |
| 3 | 105 |
| 4 | 595 |
| 5 | 10296 |
| 6 | 58311 |
| 7 | 1008910 |
| 8 | 5713890 |
| 9 | 98862891 |
| 10 | 559902916 |
| 11 | 9687554415 |
| 12 | 54864771885 |
| 13 | 949281469786 |
| 14 | 5376187741821 |
| 15 | 93019896484620 |
| 16 | 526811533926580 |
| 17 | 9115000574022981 |
| 18 | 51622154137063026 |
| 19 | 893177036357767525 |
| 20 | 5058444293898249975 |
| 21 | 87522234562487194476 |