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 | 9 |
| 2 | 79 |
| 3 | 695 |
| 4 | 6113 |
| 5 | 53769 |
| 6 | 472943 |
| 7 | 4159927 |
| 8 | 36590017 |
| 9 | 321839625 |
| 10 | 2830847119 |
| 11 | 24899654327 |
| 12 | 219013164449 |
| 13 | 1926402895881 |
| 14 | 16944315318191 |
| 15 | 149039342816695 |
| 16 | 1310924949760897 |
| 17 | 11530674997804041 |
| 18 | 101421874630758607 |
| 19 | 892089722030697143 |
| 20 | 7846670898660887393 |
| 21 | 69017995243501979145 |