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 | 48 |
| 3 | 224 |
| 4 | 2136 |
| 5 | 10976 |
| 6 | 73568 |
| 7 | 390064 |
| 8 | 2291728 |
| 9 | 12190944 |
| 10 | 67387784 |
| 11 | 356115520 |
| 12 | 1906181472 |
| 13 | 9983123936 |
| 14 | 52432319344 |
| 15 | 272227610848 |
| 16 | 1412208727736 |
| 17 | 7276913394080 |
| 18 | 37421599567712 |
| 19 | 191604936958480 |
| 20 | 978880041945808 |