Digits are nonzero squares.

Terms

a(0) =1a(1) =4a(2) =9a(3) =11a(4) =14a(5) =19a(6) =41a(7) =44a(8) =49a(9) =91a(10) =94a(11) =99a(12) =111a(13) =114a(14) =119a(15) =141a(16) =144a(17) =149a(18) =191a(19) =194a(20) =199a(21) =411a(22) =414a(23) =419a(24) =441a(25) =444a(26) =449a(27) =491a(28) =494a(29) =499