Number of distinct values of the sum of 4 products of three 0..n integers.

Terms

a(0) =5a(1) =28a(2) =90a(3) =205a(4) =409a(5) =694a(6) =1123a(7) =1668a(8) =2396a(9) =3298a(10) =4442a(11) =5741a(12) =7410a(13) =9266a(14) =11443a(15) =13937a(16) =16857a(17) =20031a(18) =23746a(19) =27694a(20) =32236a(21) =37143a(22) =42619a(23) =48390a(24) =55021a(25) =62036a(26) =69617a(27) =77815a(28) =86744a(29) =96000