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

Terms

a(0) =0a(1) =0a(2) =8a(3) =50a(4) =169a(5) =440a(6) =943a(7) =1796a(8) =3118a(9) =5090a(10) =7877a(11) =11683a(12) =16708a(13) =23253a(14) =31552a(15) =41892a(16) =54589a(17) =70030a(18) =88524a(19) =110484a(20) =136289a(21) =166434a(22) =201327a(23) =241465a(24) =287278a(25) =339444a(26) =398407a(27) =464742a(28) =539068a(29) =622021