a(n) = a(n-1) + a(n-2) + n (mod 3), with a(1)=a(2)=1.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =8a(5) =12a(6) =21a(7) =35a(8) =56a(9) =92a(10) =150a(11) =242a(12) =393a(13) =637a(14) =1030a(15) =1668a(16) =2700a(17) =4368a(18) =7069a(19) =11439a(20) =18508a(21) =29948a(22) =48458a(23) =78406a(24) =126865a(25) =205273a(26) =332138a(27) =537412a(28) =869552a(29) =1406964