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

Terms

a(0) =0a(1) =1a(2) =7a(3) =25a(4) =60a(5) =126a(6) =222a(7) =387a(8) =599a(9) =903a(10) =1295a(11) =1830a(12) =2458a(13) =3322a(14) =4317a(15) =5539a(16) =6993a(17) =8773a(18) =10766a(19) =13198a(20) =15906a(21) =19095a(22) =22707a(23) =26879a(24) =31376a(25) =36684a(26) =42500a(27) =49024a(28) =56131a(29) =64205