Up once, down twice, up three times, down four times, ...

Terms

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