Enter zero index:2
Z-transform for non-causal signal:
2*z + 4/z + 5/z^2 + z^2 + 6/z^3 + 7/z^4 + 3

Inverse Z-transform for non-causal signal:
4*kroneckerDelta(n - 1, 0) + 5*kroneckerDelta(n - 2, 0) + 6*kroneckerDelta(n - 3, 0) + 7*kroneckerDelta(n - 4, 0) + 3*kroneckerDelta(n, 0) + iztrans(z^2, z, n) + 2*iztrans(z, z, n)