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 | 3 |
| 2 | 30 |
| 3 | 372 |
| 4 | 5112 |
| 5 | 74448 |
| 6 | 1125408 |
| 7 | 17461440 |
| 8 | 276193152 |
| 9 | 4433878272 |
| 10 | 72022049280 |
| 11 | 1181146106880 |
| 12 | 19524892723200 |
| 13 | 324921616773120 |
| 14 | 5438136568504320 |
| 15 | 91467357685235712 |
| 16 | 1545090682931085312 |
| 17 | 26199310348842762240 |
| 18 | 445746455962332561408 |
| 19 | 7606624602795641929728 |