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 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 7 |
| 4 | 51 |
| 5 | 506 |
| 6 | 6843 |
| 7 | 118581 |
| 8 | 2504855 |
| 9 | 62370529 |
| 10 | 1788082153 |
| 11 | 57997339632 |
| 12 | 2099638691439 |
| 13 | 83922479506503 |
| 14 | 3670657248913385 |
| 15 | 174387350448735877 |
| 16 | 8942472292255441103 |
| 17 | 492294103555090048458 |
| 18 | 28958704109012732921523 |