Number of (w,x,y,z) with all terms in {1,...,n} and w<=2x and y>3z.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =14a(5) =42a(6) =90a(7) =200a(8) =364a(9) =585a(10) =960a(11) =1440a(12) =2052a(13) =2926a(14) =4004a(15) =5280a(16) =7000a(17) =9000a(18) =11340a(19) =14280a(20) =17670a(21) =21483a(22) =26180a(23) =31416a(24) =37296a(25) =44252a(26) =52000a(27) =60480a(28) =70434a(29) =81270