a(n) = (3^(6*n) - 2^(6*n))/35.A198412a(n) = (3^(6*n) - 2^(6*n))/35.Terms a(0) =0a(1) =19a(2) =15067a(3) =11061667a(4) =8068935979External referencesoeis: A198412