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 | 1 |
| 3 | 3 |
| 4 | 14 |
| 5 | 74 |
| 6 | 572 |
| 7 | 6564 |
| 8 | 125120 |
| 9 | 4147832 |
| 10 | 247183688 |
| 11 | 26814414976 |
| 12 | 5327509126272 |
| 13 | 1946813194004224 |
| 14 | 1313879013920844480 |
| 15 | 1644521424392726492800 |
| 16 | 3833402238753872010743808 |
| 17 | 16708198671847617602943683072 |
| 18 | 136682601082422255664288717142080 |