Motzkin numbers A001006 read mod 3.

Terms

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