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 | 12 |
| 1 | 120 |
| 2 | 1008 |
| 3 | 8160 |
| 4 | 65472 |
| 5 | 524160 |
| 6 | 4194048 |
| 7 | 33553920 |
| 8 | 268434432 |
| 9 | 2147481600 |
| 10 | 17179865088 |
| 11 | 137438945280 |
| 12 | 1099511611392 |
| 13 | 8796092989440 |
| 14 | 70368744112128 |
| 15 | 562949953290240 |
| 16 | 4503599627108352 |
| 17 | 36028797018439680 |
| 18 | 288230376150663168 |
| 19 | 2305843009211596800 |
| 20 | 18446744073705357312 |