How to make a for loop with matrices using n?

I am trying to make a matrix that is easy for me to change it's dimension while it's overall appearance stays the same. However, matlab does not seem to like the k=1:n part of my code below. Any tips on how to fix it without putting 10 instead of n? I do not get any error no matter how long I let the program run; the matrix simply stays a zero matrix.

n=10;
A=zeros(n,n);
n=10;
for k=1:n
    A(k,k)=2;
end

for k=1:(n-1)
    A(k,k+1)=-1;
end

for k=1:(n-1)
    A(k+1,k)=-1;
end
A(1,1)=1;

Answer 1

[Stephen23]

>> n = 10;
>> A = toeplitz([2,-1,zeros(1,n-2)])
A =
   2  -1   0   0   0   0   0   0   0   0
  -1   2  -1   0   0   0   0   0   0   0
   0  -1   2  -1   0   0   0   0   0   0
   0   0  -1   2  -1   0   0   0   0   0
   0   0   0  -1   2  -1   0   0   0   0
   0   0   0   0  -1   2  -1   0   0   0
   0   0   0   0   0  -1   2  -1   0   0
   0   0   0   0   0   0  -1   2  -1   0
   0   0   0   0   0   0   0  -1   2  -1
   0   0   0   0   0   0   0   0  -1   2

[Cassandra Haynes]

Thank you!