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PROJECT EULER · #0403

Lattice Points Enclosed by Parabola and Line

Statement only · UnsolvedOriginal problem ↗

For integers a and b, we define D(a,b) as the domain enclosed by the parabola y=x2 and the line y=ax+b:
D(a,b)={(x,y)x2yax+b}.

L(a,b) is defined as the number of lattice points contained in D(a,b).
For example, L(1,2)=8 and L(2,1)=1.

We also define S(N) as the sum of L(a,b) for all the pairs (a,b) such that the area of D(a,b) is a rational number and |a|,|b|N.
We can verify that S(5)=344 and S(100)=26709528.

Find S(1012). Give your answer mod 108.

Write-up coming later

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