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 | 1 |
| 2 | 6 |
| 3 | 57 |
| 4 | 748 |
| 5 | 12565 |
| 6 | 257526 |
| 7 | 6232765 |
| 8 | 173980920 |
| 9 | 5502613833 |
| 10 | 194477548330 |
| 11 | 7596028355641 |
| 12 | 324920533473108 |
| 13 | 15106155118606045 |
| 14 | 758463525318426942 |
| 15 | 40901033617318501845 |
| 16 | 2357682497456804486896 |
| 17 | 144670077586483815863569 |
| 18 | 9414952083720893890165842 |
| 19 | 647715776085173413399687633 |