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Riesel number
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A Riesel number is a value of k such that k•2^{n}1 is always composite for all natural numbers.
Using the same method presented in the Sierpiński problem article, Hans Riesel found in 1956 that 509203•2^{n}1 is always composite.
In order to demonstrate whether 509203 is the smallest Riesel number or not (the Riesel problem 1), a distributed computing project was created named Riesel Sieve.
See also
 Riesel and Proth Prime Database
 Riesel problem 1
 Riesel prime
 15,000 Riesel numbers in the sequence A101036 in OEIS
 Riesel numbers
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