[ n(n-1)/32 ].

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =1a(8) =1a(9) =2a(10) =2a(11) =3a(12) =4a(13) =4a(14) =5a(15) =6a(16) =7a(17) =8a(18) =9a(19) =10a(20) =11a(21) =13a(22) =14a(23) =15a(24) =17a(25) =18a(26) =20a(27) =21a(28) =23a(29) =25