Numbers occurring twice in A068627.

Terms

a(0) =0a(1) =60a(2) =216a(3) =468a(4) =816a(5) =1260a(6) =1800a(7) =2436a(8) =3168a(9) =3996a(10) =4920a(11) =5940a(12) =7056a(13) =8268a(14) =9576a(15) =10980a(16) =12480a(17) =14076a(18) =15768a(19) =17556a(20) =19440a(21) =21420a(22) =23496a(23) =25668a(24) =27936a(25) =30300a(26) =32760a(27) =35316a(28) =37968a(29) =40716