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) =12a(5) =38a(6) =81a(7) =185a(8) =336a(9) =549a(10) =900a(11) =1365a(12) =1944a(13) =2794a(14) =3822a(15) =5070a(16) =6720a(17) =8680a(18) =10935a(19) =13821a(20) =17100a(21) =20853a(22) =25410a(23) =30569a(24) =36288a(25) =43148a(26) =50700a(27) =59076a(28) =68796a(29) =79506