Riesel number
= Riesel number
{wiki=Riesel_number}
A Riesel number is a natural number \\( k \\) such that there exists an integer \\( n \\) for which the expression \\( n \\times 2^n - k \\) is composite for all integers \\( n \\) greater than or equal to some starting point \\( N \\).