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 | 8 |
| 3 | 63 |
| 4 | 624 |
| 5 | 7775 |
| 6 | 117648 |
| 7 | 2097151 |
| 8 | 43046720 |
| 9 | 999999999 |
| 10 | 25937424600 |
| 11 | 743008370687 |
| 12 | 23298085122480 |
| 13 | 793714773254143 |
| 14 | 29192926025390624 |
| 15 | 1152921504606846975 |
| 16 | 48661191875666868480 |
| 17 | 2185911559738696531967 |
| 18 | 104127350297911241532840 |
| 19 | 5242879999999999999999999 |
| 20 | 278218429446951548637196400 |
| 21 | 15519448971100888972574851071 |