Number of (w,x,y,z) with all terms in {1,...,n} and w>=2x and y>3z.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =4a(5) =12a(6) =27a(7) =60a(8) =112a(9) =180a(10) =300a(11) =450a(12) =648a(13) =924a(14) =1274a(15) =1680a(16) =2240a(17) =2880a(18) =3645a(19) =4590a(20) =5700a(21) =6930a(22) =8470a(23) =10164a(24) =12096a(25) =14352a(26) =16900a(27) =19656a(28) =22932a(29) =26460