Odd squares in which parity of digits alternates.

Terms

a(0) =1a(1) =9a(2) =25a(3) =49a(4) =81a(5) =121a(6) =169a(7) =361a(8) =529a(9) =729a(10) =961a(11) =4761a(12) =6561a(13) =12321a(14) =12769a(15) =14161a(16) =16129a(17) =18769a(18) =32761a(19) =34969a(20) =56169a(21) =72361a(22) =74529a(23) =76729a(24) =78961a(25) =96721a(26) =212521a(27) =214369a(28) =290521a(29) =436921