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 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 121 |
| 6 | 721 |
| 7 | 2521 |
| 8 | 6721 |
| 9 | 196561 |
| 10 | 3659041 |
| 11 | 29993041 |
| 12 | 159762241 |
| 13 | 1686639241 |
| 14 | 60298558321 |
| 15 | 987112886761 |
| 16 | 9315623640961 |
| 17 | 76611297104161 |
| 18 | 2454331471018561 |
| 19 | 69805324167893281 |
| 20 | 1086439146068753281 |
| 21 | 11530308934656915481 |