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 | 1 |
| 2 | 1 |
| 3 | 8 |
| 4 | 60 |
| 5 | 624 |
| 6 | 7735 |
| 7 | 117648 |
| 8 | 2096640 |
| 9 | 43046640 |
| 10 | 999989991 |
| 11 | 25937424600 |
| 12 | 743008120140 |
| 13 | 23298085122480 |
| 14 | 793714765724595 |
| 15 | 29192926025339776 |
| 16 | 1152921504338411520 |
| 17 | 48661191875666868480 |
| 18 | 2185911559727674682148 |
| 19 | 104127350297911241532840 |
| 20 | 5242879999999487999992020 |