a(n) is the number of regular hexagons with all six vertices (x,y,z) in the set {1,2,...,n}^3.

Terms

a(0) =0a(1) =0a(2) =0a(3) =4a(4) =32a(5) =116a(6) =320a(7) =728a(8) =1472a(9) =2796a(10) =5056a(11) =8584a(12) =13792a(13) =21136a(14) =31168a(15) =45464a(16) =64704a(17) =90036a(18) =122784a(19) =164472a(20) =216864a(21) =281584a(22) =360416a(23) =457400a(24) =574304a(25) =714644a(26) =881312a(27) =1077612a(28) =1306720a(29) =1575088