a(1) = 1; a(n+1) is the smallest integer > 0 that cannot be obtained from the integers {a(1), ..., a(n)} using each number at most once and the operators +, -, *, /, where intermediate subexpressions must be integers.

A071115

a(1) = 1; a(n+1) is the smallest integer > 0 that cannot be obtained from the integers {a(1), ..., a(n)} using each number at most once and the operators +, -, *, /, where intermediate subexpressions must be integers.