Even numbers in which parity of digits alternates.

Terms

a(0) =0a(1) =2a(2) =4a(3) =6a(4) =8a(5) =10a(6) =12a(7) =14a(8) =16a(9) =18a(10) =30a(11) =32a(12) =34a(13) =36a(14) =38a(15) =50a(16) =52a(17) =54a(18) =56a(19) =58a(20) =70a(21) =72a(22) =74a(23) =76a(24) =78a(25) =90a(26) =92a(27) =94a(28) =96a(29) =98