/*
* for every divisor d of n, d+n/d is prime.
*/
public bool IsPrimeGenerating(long number)
{
if (number % 2 == 1)
{
return(false);
}
/*
* for (long divisor1 = 2; divisor1 < number; divisor1++)
* {
* long divisor2 = number / divisor1;
* if (divisor1 > divisor2) return true;
*
* if (number % divisor1 == 0 )
* {
*
*
*
* if (!primeDictionary.ContainsKey(divisor1 + divisor2)) return false;
* }
*
*
* }
*
* return true;
*/
List <long> divisors = Divisors.GetAllUniqueDivisorsIn(number);
int len = divisors.Count();
if (len % 2 == 1)
{
return(false);
}
//if (len == 2)
// return !primeDictionary.ContainsKey(number);
if (number == 442)
{
var aa = 1;
}
// List<long> liste = divisors.Select(d => d + number / d).Distinct().ToList();
List <long> liste = divisors.Take(len).Select(d => d + number / d).Distinct().ToList();
// List<long> liste = divisors.Take(len/2).ToList();
// return liste.All(d => Primes.IsPrime(d, primeliste));
// return liste.All(d => primeDictionary.ContainsKey(d));
return(liste.All(d => primeDictionary.ContainsKey(d)));
}
public long GetFirstWithNumbersOfDivisors(long above)
{
foreach (var nextTriangularNumber in TriangleNumber.Iterastor())
{
var allUniqueDivisors = Divisors.GetAllUniqueDivisorsIn(nextTriangularNumber);
if (allUniqueDivisors.Count > above)
{
return(nextTriangularNumber);
}
}
return(-1);
}
