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 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 41 |
| 5 | 425 |
| 6 | 4287 |
| 7 | 45941 |
| 8 | 541219 |
| 9 | 7071501 |
| 10 | 102193755 |
| 11 | 1622448861 |
| 12 | 28090940363 |
| 13 | 526856206877 |
| 14 | 10641335658891 |
| 15 | 230283166014653 |
| 16 | 5315654596751659 |
| 17 | 130370766738143517 |
| 18 | 3385534662263335179 |
| 19 | 92801587315936355325 |
| 20 | 2677687796232803000171 |
| 21 | 81124824998464533181661 |