public static long ConsecutivePrimeSum()
{
long consecutivePrime = 0;
List <long> primesList = PrimeHelpers.ExecuteSieveofEratosthenes(1000000);
long currentPrime = primesList[primesList.Count - 1];
long maxVal = 0;
for (var j = (primesList.Count - 1) - 1; j >= 0; j--)
{
long currentSum = 0;
for (var k = j; k >= 0 && currentSum <= currentPrime; k--)
{
currentSum += primesList[k];
if (j - k > maxVal)
{
maxVal = j - k;
if (primesList.Contains(currentSum))
{
consecutivePrime = currentSum;
}
}
}
}
return(consecutivePrime);
}
public static int DistinctPrimesFactors()
{
int number = 2 * 3 * 5 * 7;
int foundCount = 0;
List <long> primeList = PrimeHelpers.ExecuteSieveofEratosthenes(1000000);
while (foundCount < 4)
{
long tempNumber = number;
long prime = primeList[0];
int primeCount = 0;
bool isDifferentPrime = false;
int primeIndex = 0;
primeCount = tempNumber % prime == 0 ? 1 : 0;
while (tempNumber > 1)
{
if (tempNumber % prime == 0)
{
tempNumber /= prime;
if (isDifferentPrime)
{
primeCount++;
isDifferentPrime = false;
}
}
else
{
primeIndex++;
prime = primeList[primeIndex];
isDifferentPrime = true;
}
}
number++;
if (tempNumber == 1 && primeCount == 4)
{
foundCount++;
}
else
{
foundCount = 0;
}
}
return(number - 4);
}
public static long PandigitalPrime()
{
long result = 0;
var primeList = PrimeHelpers.ExecuteSieveofEratosthenes(987654321);
for (var i = primeList.Count - 1; i >= 0; i--)
{
if (MathHelpers.IsPandigital(primeList[i]))
{
result = primeList[i];
break;
}
}
return(result);
}