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) =8a(4) =28a(5) =88a(6) =186a(7) =378a(8) =660a(9) =1104a(10) =1700a(11) =2575a(12) =3660a(13) =5148a(14) =6972a(15) =9310a(16) =12096a(17) =15616a(18) =19656a(19) =24624a(20) =30330a(21) =37100a(22) =44770a(23) =53845a(24) =63888a(25) =75600a(26) =88608a(27) =103428a(28) =119756a(29) =138376