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 | 1 |
| 3 | 4 |
| 4 | 22 |
| 5 | 138 |
| 6 | 998 |
| 7 | 8174 |
| 8 | 74898 |
| 9 | 759634 |
| 10 | 8451862 |
| 11 | 102381222 |
| 12 | 1341503546 |
| 13 | 18907621562 |
| 14 | 285259758366 |
| 15 | 4587192222958 |
| 16 | 78327809126818 |
| 17 | 1415429225667234 |
| 18 | 26987142531214118 |
| 19 | 541434621007942454 |
| 20 | 11402270678456333322 |