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

Terms

a(0) =0a(1) =0a(2) =1a(3) =14a(4) =46a(5) =118a(6) =267a(7) =497a(8) =871a(9) =1438a(10) =2215a(11) =3273a(12) =4713a(13) =6526a(14) =8844a(15) =11758a(16) =15303a(17) =19590a(18) =24796a(19) =30862a(20) =38053a(21) =46457a(22) =56115a(23) =67206a(24) =79971a(25) =94357a(26) =110628a(27) =128979a(28) =149481a(29) =172291