public static int ProductOfCoefficientOfQuadraticFormulaProducingMorePrimeNumbers()
{
var maxPrimeNumbers = int.MinValue;
int aValue = int.MinValue;
int bValue = int.MinValue;
var primesUntil999 = PrimeNumbers.PrimesUntilN(999);
for (int a = -999; a < 1000; a++)
{
for (int b = 2; b <= 999; b++)
{
if (primesUntil999[b])
{
int n;
for (n = 1; PrimeNumbers.IsPrimeNumber(n * n + a * n + b); n++)
{
;
}
if (n > maxPrimeNumbers)
{
maxPrimeNumbers = n;
aValue = a;
bValue = b;
}
}
}
}
return(aValue * bValue);
}
public static long SumPrimesBelowN(int num)
{
var primes = PrimeNumbers.PrimesUntilN(num - 1);
long sum = 2;
for (int i = 3; i < primes.Length; i += 2)
{
if (primes[i])
{
sum += i;
}
}
return(sum);
}
public static int ConsecutivePrimeSum(int num)
{
var primes = PrimeNumbers.PrimesUntilN(num);
int greatestPrimeSum = 0;
int largestStreak = 0;
for (int i = 0; i < primes.Length; i++)
{
if (primes[i])
{
int currentStreak = 0;
int currentSum = 0;
for (int j = i; j < primes.Length; j++)
{
if (primes[j])
{
currentSum += j;
if (currentSum >= num)
{
break;
}
currentStreak++;
if (primes[currentSum] && currentStreak > largestStreak)
{
largestStreak = currentStreak;
greatestPrimeSum = currentSum;
}
}
}
}
}
return(greatestPrimeSum);
}
public E035_Circular_primes(int threshold)
{
_threshold = threshold;
_primeNumbers = PrimeNumbers.PrimesUntilN(_threshold - 1);
}