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%I #7 Nov 02 2019 19:58:49
%S 1,1,1,1,1,0,1,1,1,0,1,0,1,0,0,1,1,0,1,0,0,0,1,0,1,0,1,0,1,-1,1,1,0,0,
%T 0,1,1,0,0,0,1,-1,1,0,0,0,1,0,1,0,0,0,1,0,0,0,0,0,1,0,1,0,0,1,0,-1,1,
%U 0,0,-1,1,2,1,0,0,0,0,-1,1,0,1,0,1,0,0
%N a(n) = sigma_0(n) - omega(n) * nu(n), where sigma_0 = A000005, nu = A001221, omega = A001222.
%F a(n) = A000005(n) - A001222(n) * A001221(n).
%e a(144) = sigma_0(144) - omega(144) * nu(144) = 15 - 6 * 2 = 3.
%t Table[DivisorSigma[0,n]-PrimeOmega[n]*PrimeNu[n],{n,100}]
%Y Positions of first appearances are A328962.
%Y Zeros are A328956.
%Y Nonzeros are A328957.
%Y omega(n) * nu(n) is A113901(n).
%Y (omega(n) - 1) * nu(n) is A307409(n).
%Y sigma_0(n) - 2 - (omega(n) - 1) * nu(n) is A328959(n).
%Y Cf. A000005, A001221, A001222, A112798, A124010, A323023, A328960, A328961, A328963, A328964.
%K sign
%O 1,72
%A _Gus Wiseman_, Nov 02 2019
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