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PROJECT EULER · #0621

Expressing an Integer as the Sum of Triangular Numbers

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Gauss famously proved that every positive integer can be expressed as the sum of three triangular numbers (including 0 as the lowest triangular number). In fact most numbers can be expressed as a sum of three triangular numbers in several ways.

Let G(n) be the number of ways of expressing n as the sum of three triangular numbers, regarding different arrangements of the terms of the sum as distinct.

For example, G(9)=7, as 9 can be expressed as: 3+3+3, 0+3+6, 0+6+3, 3+0+6, 3+6+0, 6+0+3, 6+3+0.
You are given G(1000)=78 and G(106)=2106.

Find G(17526×109).

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