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PROJECT EULER · #0685

Inverse Digit Sum II

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Writing down the numbers which have a digit sum of 10 in ascending order, we get: 19,28,37,46,55,64,73,82,91,109,118,

Let f(n,m) be the mth occurrence of the digit sum n. For example, f(10,1)=19, f(10,10)=109 and f(10,100)=1423.

Let S(k)=n=1kf(n3,n4). For example S(3)=7128 and S(10)32287064mod1000000007.

Find S(10000) modulo 1000000007.

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