Triangle read by rows: Pascal's triangle (A007318) mod 4.

Terms

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