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) =12a(3) =57a(4) =185a(5) =459a(6) =974a(7) =1830a(8) =3168a(9) =5158a(10) =7957a(11) =11766a(12) =16830a(13) =23378a(14) =31689a(15) =42041a(16) =54774a(17) =70218a(18) =88757a(19) =110720a(20) =136558a(21) =166715a(22) =201620a(23) =241761a(24) =287646a(25) =339854a(26) =398829a(27) =465198a(28) =539557a(29) =622513