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

Terms

a(0) =0a(1) =0a(2) =3a(3) =14a(4) =48a(5) =114a(6) =243a(7) =444a(8) =768a(9) =1220a(10) =1875a(11) =2730a(12) =3888a(13) =5334a(14) =7203a(15) =9464a(16) =12288a(17) =15624a(18) =19683a(19) =24390a(20) =30000a(21) =36410a(22) =43923a(23) =52404a(24) =62208a(25) =73164a(26) =85683a(27) =99554a(28) =115248a(29) =132510