Square previous term and then delete digits of previous term.

Terms

a(0) =2a(1) =4a(2) =16a(3) =25a(4) =6a(5) =3a(6) =9a(7) =81a(8) =656a(9) =43033a(10) =18518989a(11) =3422322a(12) =11718787168a(13) =33299240224a(14) =118856557176a(15) =42330949a(16) =17161a(17) =29449992a(18) =867300880006a(19) =522114591215a(20) =760366360676