581970

Appears in sequences

• Number of distinct values taken by 4^4^...^4 (with n 4's and parentheses inserted in all possible ways).at n=16A003019
• G.f.: A(x) = A_1 where A_1 = 1/[1 - x*(A_2)^2], A_2 = 1/[1 - x^2*(A_3)^2], A_3 = 1/[1 - x^3*(A_4)^2], ... A_n = 1/[1 - x^n*(A_{n+1})^2] for n>=1.at n=20A132332