Triangle T(n,k) = gcd(n,k)-binomial(n,k), 0<=k<=n.

Terms

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