a(n) = Successive numbers x such that value of function N(9^x-1,9^x) defined as product of different prime factors of product 9^x(9^x-1) is equal 3(9^x-1)/4

Maximal value of radical function N(a,b,9^x) for every number 9^x and every combination of partitions a,b such that a + b = 9^x and GCD[a,b,3]=1 is never less than 3(9^x-1)/4 and is exactly equal 3(9^x-1)/4 for exponents x in this sequence. - Artur Jasinski.

Conjecture (Artur Jasinski): This sequence is infinite.