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

Terms

a(0) =0a(1) =0a(2) =3a(3) =25a(4) =98a(5) =260a(6) =571a(7) =1089a(8) =1898a(9) =3084a(10) =4755a(11) =7017a(12) =9994a(13) =13836a(14) =18691a(15) =24705a(16) =32066a(17) =40964a(18) =51579a(19) =64145a(20) =78850a(21) =95956a(22) =115723a(23) =138385a(24) =164170a(25) =193436a(26) =226467a(27) =263521a(28) =304930a(29) =351076