In complexity theory, n is based on the length of the binary encoding of the input, NOT the decimal value as was used here. Therefore, the x-axis should be based on n = log2(k), for each number k.

Overlooking this would lead one to believe there are known algorithms that solve NP-C problems in polynomial time (e.g., knapsack problem can be solved in polynomial time with respect to the decimal values of its inputs, but exponential with respect to the length of the binary encoding).