Why is there this error in the code?

Using MATLAB

gn=3

sn=17

I =(gn*60)+(sn*2)

A = 250/(I + 100)

T = 1/(5*I)

a0 =(A/2)

number_of_points = 100

step_size = T/number_of_points

t = 0:step_size:T

f = a0

N=100

n=1:N

an = 0

bn = (A)/(n*pi)*(1 - cos(n*pi))

f = f + an*cos( n*pi*t/(T/2) ) + bn*sin( n*pi*t/(T/2) )

figure(1)

plot(t,f)

hold on

square_wave_f=A/2 + A/2*square(2*pi*t/T)

line_style ='r-'

plot(t,square_wave_f,line_style)

hold off