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 | 3 |
| 3 | 48 |
| 4 | 675 |
| 5 | 9408 |
| 6 | 131043 |
| 7 | 1825200 |
| 8 | 25421763 |
| 9 | 354079488 |
| 10 | 4931691075 |
| 11 | 68689595568 |
| 12 | 956722646883 |
| 13 | 13325427460800 |
| 14 | 185599261804323 |
| 15 | 2585064237799728 |
| 16 | 36005300067391875 |
| 17 | 501489136705686528 |
| 18 | 6984842613812219523 |
| 19 | 97286307456665386800 |
| 20 | 1355023461779503195683 |