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 | 0 |
| 4 | 3 |
| 5 | 10 |
| 6 | 355 |
| 7 | 6986 |
| 8 | 297619 |
| 9 | 15077658 |
| 10 | 1120452771 |
| 11 | 111765799882 |
| 12 | 15350524923547 |
| 13 | 2875055248515242 |
| 14 | 738416821509929731 |
| 15 | 260316039943139322858 |
| 16 | 126430202628042630866787 |
| 17 | 84814075550928212558332858 |
| 18 | 78847417416749666369637926851 |