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 | 144 |
| 3 | 1068 |
| 4 | 9936 |
| 5 | 55500 |
| 6 | 640992 |
| 7 | 3562968 |
| 8 | 31412208 |
| 9 | 228238488 |
| 10 | 227429400 |
| 11 | 220709400 |
| 12 | 1922263344 |
| 13 | 11432420652 |
| 14 | 11150046252 |
| 15 | 75796404672 |
| 16 | 94197649008 |
| 17 | 96503566608 |
| 18 | 546394287000 |
| 19 | 419850417612 |
| 20 | 4615731883344 |
| 21 | 3939440152944 |