How to implement a for loop for a equation and plot the values on a graph?

How can I correct the array values of 'fncT' when t becomes bigger than 19, the answers become incorrect for some reason. What is wrong with this and how can I solve this? I want a repeating set of answers up to 100 values. Also how can I possible put this in a for loop and plot the values on the graph?

This is the code:

A = 7;

P = 100;

M = 15;

t = 1:1:P

fncT = (A.^t) - floor(A.^t/M)*M; % Alternative to mod() function

plot(t,fncT)

Answer 1

[David Hill]

Need to use symbolics because 7^100 is too big.

A = sym(7);
P = 100;
M = 15;
t = 1:1:P
fncT = double((A.^t) - floor(A.^t/M)*M);
plot(t,fncT)