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

Terms

a(0) =1a(1) =13a(2) =113a(3) =925a(4) =6577a(5) =42205a(6) =252673a(7) =1405325a(8) =7259297a(9) =35372141a(10) =164379601a(11) =733618493a(12) =3146718929a(13) =12990499005a(14) =51718535393a(15) =198914813101a(16) =740760081985