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 | 12 |
| 2 | 204 |
| 3 | 2928 |
| 4 | 40140 |
| 5 | 547512 |
| 6 | 7535472 |
| 7 | 105077376 |
| 8 | 1484848332 |
| 9 | 21237645000 |
| 10 | 306972655704 |
| 11 | 4477160465856 |
| 12 | 65802123629424 |
| 13 | 973487343836448 |
| 14 | 14483651478207360 |
| 15 | 216550246159148928 |
| 16 | 3251660678391659724 |
| 17 | 49011343741651501800 |
| 18 | 741221951008966181160 |
| 19 | 11243583961952559386400 |