Horizontally symmetric numbers.

Terms

a(0) =0a(1) =1a(2) =3a(3) =8a(4) =10a(5) =11a(6) =13a(7) =18a(8) =30a(9) =31a(10) =33a(11) =38a(12) =80a(13) =81a(14) =83a(15) =88a(16) =100a(17) =101a(18) =103a(19) =108a(20) =110a(21) =111a(22) =113a(23) =118a(24) =130a(25) =131a(26) =133a(27) =138a(28) =180a(29) =181