a(n) = abs(a(n-1) - 3*a(n-2)) with a(1)=a(2)=1.

Terms

a(0) =1a(1) =1a(2) =2a(3) =1a(4) =5a(5) =2a(6) =13a(7) =7a(8) =32a(9) =11a(10) =85a(11) =52a(12) =203a(13) =47a(14) =562a(15) =421a(16) =1265a(17) =2a(18) =3793a(19) =3787a(20) =7592a(21) =3769a(22) =19007a(23) =7700a(24) =49321a(25) =26221a(26) =121742a(27) =43079a(28) =322147a(29) =192910