Make Sequence Function go Diagonal

Hi ,how would i make this function go diagonal?,any help would be great

n = input ('sequence_matrix_');
fibb=[1,3:n];

for i=3:n
    fibb(i)=fibb(i-1)*3+(i)-2;
end

fibb

[Sam Chak]

The original question may be beneficial for people who wish to learn how to create a diagonal matrix.

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Sameer Pujari]

Just do this small change

n = input ('sequence_matrix_');
fibb=[1,3:n];
for i=3:n
    fibb(i)=fibb(i-1)*3+(i)-2;
end
diag(fibb)

[Ainars Cernavskis]

o it was that simple , thank you .

Answer 2

[Walter Roberson]

n = input ('sequence_matrix_');
fibb = diag([1,3:n]);

for i=3:n
    fibb(i,i) = fibb(i-1,i-1)*3+(i)-2;
end

fibb