TypeError: only size-1 arrays can be converted to Python scalar: input to function raises error if from a list

Question

I have the following code:

N = [16, 32, 64] #number of particles
K = [0.2, 0.3, 0.4, 0.5, 0.6, 0.7] #coupling constant
ising = np.ones((N)) #all aligned, isin