a(1)=0 a(2)=3 a(n+2)=(a(n+1)+a(n))/3 if (a(n+1)+a(n)==0 (mod 3)); a(n+2)=a(n+1)+a(n) otherwise.

Terms

a(0) =0a(1) =3a(2) =1a(3) =4a(4) =5a(5) =3a(6) =8a(7) =11a(8) =19a(9) =10a(10) =29a(11) =13a(12) =14a(13) =9a(14) =23a(15) =32a(16) =55a(17) =29a(18) =28a(19) =19a(20) =47a(21) =22a(22) =23a(23) =15a(24) =38a(25) =53a(26) =91a(27) =48a(28) =139a(29) =187