Number of ways that number n can be represented as the sum of three nonzero repdigit numbers.

0, 1, 2, 3, 4, 5, 7, 8, 10, 12, 13, 15, 16, 17, 17, 18, 17, 17, 16, 15, 13, 12, 11, 10, 9, 8, 7, 7, 6, 6, 6, 6, 5, 7, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 8, 7, 7, 7, 7, 7, 7, 7, 7, 7, 5, 9, 7, 7, 7, 7, 7, 7, 7, 7, 7, 5, 11, 8, 8, 8, 8, 8, 8, 8, 8, 8, 5, 12, 8, 8, 8, 8

0

The first zero term is for n = 320.

T. D. Noe, Plot of 5001 terms

T. D. Noe, Table of 5001 terms

Eric W. Weisstein, MathWorld: Repdigit

(Mma) maxLen = 4; repNums = Union[Flatten[Table[FromDigits[Table[a, {len}]], {a, 0, 9}, {len, maxLen}]]]; Join[{0}, Table[Length[IntegerPartitions[n, 3, Rest[repNums]]], {n, 5000}]]

nonn,base

T. D. Noe, Jul 27 2016