Squares using only the prime digits (2,3,5,7).

Terms

a(0) =25a(1) =225a(2) =7225a(3) =27225a(4) =55225a(5) =235225a(6) =2772225a(7) =3553225a(8) =23377225a(9) =33235225a(10) =57532225a(11) =227557225a(12) =252333225a(13) =277722225a(14) =337273225a(15) =357777225a(16) =523723225a(17) =735223225a(18) =777573225a(19) =2523555225a(20) =3325252225a(21) =3377353225a(22) =5232352225a(23) =7333353225