Number of points in N^n of norm <= 6.

Terms

a(0) =1a(1) =7a(2) =35a(3) =163a(4) =688a(5) =2673a(6) =9763a(7) =33792a(8) =111155a(9) =349122a(10) =1053323a(11) =3070003a(12) =8681103a(13) =23885604a(14) =64075075a(15) =167836570a(16) =429817326a(17) =1077457554a(18) =2646942189a(19) =6379963205a(20) =15104418023a(21) =35160248084a(22) =80550746390a(23) =181768697529