Tossup

The polynomial [read slowly] x to the n plus y to the n is irreducible over the reals if and only if n is one of these numbers. (-5[1])Every known almost perfect number is one of these numbers. (10[1]-5[1])The cardinality of the power set of any finite set is one of these numbers. (-5[2])These numbers appear (10[1])in the exponent in the formula for Fermat numbers, while Mersenne primes are defined as being one less (10[1])than these (10[1])numbers. (10[1]-5[1])The sum along any row of Pascal’s (10[1])triangle is equal to one of these numbers. These are the only integers with no odd prime factors. (-5[1])In binary, these numbers consist of a one followed by all zeros. For 10 points, name these (10[1])numbers which include 4, 8 and 16, obtained by repeated multiplication (10[1]0[2])by the smallest even number. ■END■ (0[1])

ANSWER: powers of two [accept two to the n; accept any letter in place of “n”; reject “second powers”]
<Editors, Other Science>
= Average correct buzz position

Back to tossups