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) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 15 |
| 5 | 391 |
| 6 | 16275 |
| 7 | 999391 |
| 8 | 85314915 |
| 9 | 9682617631 |
| 10 | 1411532175075 |
| 11 | 257220473522431 |
| 12 | 57317980108103715 |
| 13 | 15338554965273810271 |
| 14 | 4855172557420679314275 |
| 15 | 1794588990417909081447871 |
| 16 | 766066194581899382513514915 |
| 17 | 374061220058388896558805473311 |