A002244 Numbers that are not the sum of 3 distinct nonzero triangular numbers.
1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 15, 16, 18, 20, 21, 23, 27, 29, 33, 36, 38, 48, 51, 78, 111, 183
Offset: 1
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.