Even squares in which parity of digits alternates.

Terms

a(0) =0a(1) =4a(2) =16a(3) =36a(4) =256a(5) =676a(6) =1296a(7) =5476a(8) =7056a(9) =9216a(10) =41616a(11) =69696a(12) =87616a(13) =147456a(14) =163216a(15) =181476a(16) =329476a(17) =341056a(18) =367236a(19) =527076a(20) =541696a(21) =583696a(22) =763876a(23) =781456a(24) =929296a(25) =2143296a(26) =2509056a(27) =2547216a(28) =2903616a(29) =4145296