s(3n)-s(3n-1), where s( ) is sequence A023633.

Terms

a(0) =4a(1) =2a(2) =2a(3) =5a(4) =5a(5) =5a(6) =2a(7) =2a(8) =2a(9) =5a(10) =2a(11) =2a(12) =2a(13) =5a(14) =2a(15) =2a(16) =2a(17) =5a(18) =5a(19) =5a(20) =5a(21) =2a(22) =2a(23) =2a(24) =5a(25) =5a(26) =5a(27) =5a(28) =2a(29) =2