Strobogrammatic numbers: the same upside down.

Terms

a(0) =0a(1) =1a(2) =8a(3) =11a(4) =69a(5) =88a(6) =96a(7) =101a(8) =111a(9) =181a(10) =609a(11) =619a(12) =689a(13) =808a(14) =818a(15) =888a(16) =906a(17) =916a(18) =986a(19) =1001a(20) =1111a(21) =1691a(22) =1881a(23) =1961a(24) =6009a(25) =6119a(26) =6699a(27) =6889a(28) =6969a(29) =8008