Roots of 'squares remaining square when written backwards'.

Terms

a(0) =1a(1) =2a(2) =3a(3) =11a(4) =12a(5) =13a(6) =21a(7) =22a(8) =26a(9) =31a(10) =33a(11) =99a(12) =101a(13) =102a(14) =103a(15) =111a(16) =112a(17) =113a(18) =121a(19) =122a(20) =201a(21) =202a(22) =211a(23) =212a(24) =221a(25) =264a(26) =301a(27) =307a(28) =311a(29) =836