On the Iwasawa λ-invariant of the cyclotomic ℤ2-extension of ℚ(pq) and the 2-part of the class number of ℚ(pq,2 + 2)

In this paper, we study the Iwasawa Formula: see text-invariant of the cyclotomic Formula: see text-extension of Formula: see text, where Formula: see text are distinct odd prime numbers satisfying certain arithmetic conditions. Moreover, we obtain an upper bound of the Formula: see text-part of the class number of certain quartic number fields by calculating the Sinnott index explicitly.