public static int truncatableprimes(int n)
{
int count = 0;
int sum = 0;
PrimeFunctions.GeneratePrimesToList(1000000);
PrimeFunctions.ConvertToHash();
int i = 4;
while (count < n)
{
bool isprime = true;
List <int> trunc = CombinatoricFunctions.truncations(PrimeFunctions.PrimeList[i]);
foreach (int truncation in trunc)
{
if (!PrimeFunctions.PrimeListHash.Contains(truncation))
{
isprime = false;
break;
}
}
if (isprime)
{
count++;
sum += PrimeFunctions.PrimeList[i];
}
i++;
}
return(sum);
}
public static int SmallestMultiple(int n)
{
PrimeFunctions.GeneratePrimesTillNToList(n);
List <int> FactorList = new List <int>();
//Loop until highest multiple
for (int i = 2; i <= n; i++)
{
//Find all the factors of the number
List <int> factors = PrimeFunctions.PrimeFactor(i, false);
//If the list of factors doesn't contain the factor or as many factors, then add it to the list
foreach (int factor in factors)
{
if (MiscFunctions.ReturnDistinctCountList(factors, factor) > MiscFunctions.ReturnDistinctCountList(FactorList, factor))
{
FactorList.Add(factor);
}
}
}
//Loop through the minimum required factors and multiply them all
int mult = 1;
foreach (int factor in FactorList)
{
mult *= factor;
}
return(mult);
}
public static int CirculuarPrimes(int n)
{
PrimeFunctions.GeneratePrimesTillNToList(1000000);
PrimeFunctions.ConvertToHash();
int count = 0;
for (int i = 2; i < n; i++)
{
List <int> rots = CombinatoricFunctions.rotations(i);
bool prime = true;
foreach (int rot in rots)
{
if (!PrimeFunctions.PrimeListHash.Contains(rot))
{
prime = false;
break;
}
}
if (prime)
{
count++;
//Console.WriteLine(i);
}
}
return(count);
}
public static long SummationOfPrimes(int n)
{
List <int> primes = PrimeFunctions.GeneratePrimesTillN(2 * n);
long k = 0;
for (int i = 0; primes[i] < n; i++)
{
k += primes[i];
}
return(k);
}
public static int PandigitalPrime(int n)
{
List <int> PanPrimes = new List <int>();
PrimeFunctions.GeneratePrimesTillNToList(n);
for (int i = 0; i < PrimeFunctions.PrimeList.Count; i++)
{
if (MiscFunctions.IsPandigital(PrimeFunctions.PrimeList[i]))
{
PanPrimes.Add(PrimeFunctions.PrimeList[i]);
}
}
return(PanPrimes.Max());
}
public static int OddComposite()
{
int comp = 0;
List <int> primes = PrimeFunctions.GeneratePrimes(10000);
HashSet <int> primeshash = MiscFunctions.ListToHash(primes);
List <int> squares = SpecialSequences.squares(1000);
HashSet <int> squareshash = MiscFunctions.ListToHash(squares);
int i = 3;
bool found = false;
while (comp == 0)
{
found = false;
i += 2;
if (primeshash.Contains(i))
{
continue;
}
for (int j = 0; j < primes.Count; j++)
{
if (primes[j] > i)
{
break;
}
for (int k = 0; k < squares.Count; k++)
{
if (squares[k] * 2 > i)
{
break;
}
if (primes[j] + (squares[k] * 2) == i)
{
found = true;
}
}
}
if (!found)
{
comp = i;
}
}
return(comp);
}
public static int DistinctPrimeFactors()
{
PrimeFunctions.GeneratePrimesToList(100000);
int i = 2;
int count = 0;
while (count < 4)
{
i++;
List <int> primes = PrimeFunctions.PrimeFactor(i);
HashSet <int> factors = MiscFunctions.ListToHash(primes);
if (factors.Count == 4)
{
count++;
}
else
{
count = 0;
}
}
return(i - 3);
}
public static int QuadraticPrimes(int n)
{
PrimeFunctions.GeneratePrimesTillNToList(n * n);
PrimeFunctions.ConvertToHash();
int maxi = 0;
int maxj = 0;
int maxprimes = 0;
for (int i = (n * -1); i < n; i++)
{
for (int j = (n * -1); j < n; j++)
{
if (numquadprimes(i, j) > maxprimes)
{
maxprimes = numquadprimes(i, j);
maxi = i;
maxj = j;
}
}
}
return(maxi * maxj);
}
public static int LargestPrimeFactor(long n)
{
//Return the largest number in the list of prime factors
return(PrimeFunctions.PrimeFactor(n).Max());
}
public static int TenthousandstPrime(int n)
{
return(PrimeFunctions.NthPrime(n));
}