how to make a vector circularly simmetric?

Hello, I would like to make my vector circulary simmetric. I have something like

A=[1,5,15,50,15,5,1];

And I would like to have a matrix like this:

B=[1,1,1,1,1,1,1;
   1,5,5,5,5,5,1;
   1,5,15,15,15,5,1;
   1,5,15,50,15,5,1;
   1,5,15,15,15,5,1
   1,5,5,5,5,5,1; 
   1,1,1,1,1,1,1];

Can someone help me? Thank you in advance