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 | 1 |
| 2 | 5 |
| 3 | 40 |
| 4 | 440 |
| 5 | 6160 |
| 6 | 104720 |
| 7 | 2094400 |
| 8 | 48171200 |
| 9 | 1252451200 |
| 10 | 36321084800 |
| 11 | 1162274713600 |
| 12 | 40679614976000 |
| 13 | 1545825369088000 |
| 14 | 63378840132608000 |
| 15 | 2788668965834752000 |
| 16 | 131067441394233344000 |
| 17 | 6553372069711667200000 |
| 18 | 347328719694718361600000 |
| 19 | 19450408302904228249600000 |