Number of (w,x,y,z) with all terms in {1,...,n} and w*x<3*y*z.

Terms

a(0) =0a(1) =1a(2) =15a(3) =67a(4) =210a(5) =507a(6) =1029a(7) =1904a(8) =3225a(9) =5123a(10) =7785a(11) =11368a(12) =16023a(13) =22035a(14) =29572a(15) =38867a(16) =50233a(17) =63931a(18) =80180a(19) =99459a(20) =121947a(21) =148024a(22) =178141a(23) =212635a(24) =251805a(25) =296268a(26) =346348a(27) =402462a(28) =465175a(29) =534990