A008712 15 in base 15-n.
10, 11, 12, 13, 14, 15, 16, 17, 21, 23, 30, 33, 120, 1111, 111111111111111
Offset: 0
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.