a(1)=1, a(2)=1. a(n) = the sum of the two largest earlier terms which are both coprime to n.

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =4a(5) =2a(6) =6a(7) =2a(8) =6a(9) =2a(10) =12a(11) =2a(12) =18a(13) =2a(14) =6a(15) =2a(16) =30a(17) =2a(18) =48a(19) =2a(20) =6a(21) =2a(22) =78a(23) =2a(24) =126a(25) =2a(26) =6a(27) =2a(28) =204a(29) =2