A sequence is constructed by listing all the positive integers that containe no digit greater than 3 in ascending order:

1,2,3,10,11,12,13,20,...

Find the 2021st term of this sequence.

1 ,2 ,3 ,10 ,11 ,12 ,13 ,20 ,21 ,22 ,23 ,30 ,31 ,32 ,33 ,100...........133130 ,133131 ,133132 ,133133 ,133200 ,133201 ,133202 ,133203 ,133210 ,133211)

The 2021st term ==133,211

P.S. This sequence was calculated by computer using C++ programming language.