59 lines
1.2 KiB
C#
59 lines
1.2 KiB
C#
internal class Program
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{
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private static void Main(string[] args)
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{
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long limit = 100;
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Console.WriteLine($"The first {limit} tau numbers are:");
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long count = 0;
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for (long n = 1; count < limit; ++n)
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{
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if (IsTauNumber(n))
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{
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Console.Write($"{n, 6} ");
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++count;
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if (count % 10 == 0)
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{
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Console.WriteLine();
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}
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}
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}
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}
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private static bool IsTauNumber(long n)
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{
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return n % DivisorCount(n) == 0;
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}
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private static long DivisorCount(long n)
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{
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long total = 1;
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// Deal with powers of 2 first
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for (; (n & 1) == 0; n >>= 1)
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{
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++total;
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}
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// Odd prime factors up to the square root
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for (long p = 3; p * p <= n; p += 2)
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{
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long count = 1;
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for (; n % p == 0; n /= p)
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{
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++count;
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}
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total *= count;
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}
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// If n > 1 then it's prime
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if (n > 1)
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{
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total *= 2;
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}
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return total;
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}
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}
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