public BigInteger Solve(BigInteger?input = null)
{
BigInteger result = 0;
bool[] primesUnderLimit = PrimeHelper.FindPrimesUnderLimit(10001);
for (int i = 2; i < 10000; i++)
{
if (primesUnderLimit[i])
{
continue;
}
BigInteger sumOfDivisors = DivisorsHelper.SumOfDivisors(i, primesUnderLimit) - i;
if (sumOfDivisors < 10000 &&
sumOfDivisors != i &&
DivisorsHelper.SumOfDivisors((int)sumOfDivisors, primesUnderLimit) - sumOfDivisors == i)
{
result += i;
}
}
return(result);
}
