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MATH 25  FALL 1998
FREQUENTLY ASKED QUESTIONS
This page will contain questions that are asked frequently in office hours. Check here first when you have a question.
 Posted 1 October 1998:
 If you get Ulam numbers by taking the sum of already known Ulam numbers, wouldn't every integer be an Ulam number? No. Here's how the Ulam numbers work. We know that the first two Ulam numbers are 1 and 2. Now, for every integer greater than or equal to 3, we check whether that integer can be expressed uniquely as the sum of two distinct Ulam numbers. For example, 3 is an Ulam number since 3=1+2 and 3 cannot be expressed as the sum of any other two Ulam numbers. The integer 4 is also an Ulam number since 4=1+3 and 4 cannot be expressed as the sum of any other two distinct Ulam numbers. But 5 is not an Ulam number, since 5=1+4=3+2.
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