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

Terms

a(0) =0a(1) =1a(2) =8a(3) =31a(4) =87a(5) =185a(6) =353a(7) =605a(8) =978a(9) =1471a(10) =2123a(11) =2958a(12) =4028a(13) =5308a(14) =6864a(15) =8733a(16) =10947a(17) =13491a(18) =16452a(19) =19837a(20) =23711a(21) =28047a(22) =32929a(23) =38376a(24) =44498a(25) =51181a(26) =58569a(27) =66699a(28) =75588a(29) =85260