Triangle, row sums = A008683, the Mobius sequence.

Terms

a(0) =1a(1) =1a(2) =-2a(3) =1a(4) =-4a(5) =2a(6) =1a(7) =-6a(8) =6a(9) =-1a(10) =1a(11) =-8a(12) =12a(13) =-4a(14) =-2a(15) =1a(16) =-10a(17) =20a(18) =-10a(19) =-10a(20) =10a(21) =1a(22) =-12a(23) =30a(24) =-20a(25) =-30a(26) =60a(27) =-30a(28) =1a(29) =-14