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

Terms

a(0) =0a(1) =1a(2) =15a(3) =62a(4) =176a(5) =395a(6) =775a(7) =1382a(8) =2296a(9) =3595a(10) =5407a(11) =7822a(12) =10968a(13) =14995a(14) =20063a(15) =26286a(16) =33896a(17) =43043a(18) =53951a(19) =66798a(20) =81832a(21) =99251a(22) =119375a(23) =142382a(24) =168592a(25) =198251a(26) =231711a(27) =269190a(28) =311088a(29) =357675