Strobogrammatic numbers: numbers that are the same upside down (using calculator-style numerals).

Terms

a(0) =0a(1) =1a(2) =2a(3) =5a(4) =8a(5) =11a(6) =22a(7) =55a(8) =69a(9) =88a(10) =96a(11) =101a(12) =111a(13) =121a(14) =151a(15) =181a(16) =202a(17) =212a(18) =222a(19) =252a(20) =282a(21) =505a(22) =515a(23) =525a(24) =555a(25) =585a(26) =609a(27) =619a(28) =629a(29) =659