How to do the following in a simpler and smarter way?

The following code prepares the labels for some classes. We have standard 12 elements of 1,2,3,...,21 one after another. Now is there any other way to get this array than putting them one by one by hand.

c=[1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,3,3,...
      4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,...
      7,7,7,7,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,8,8,8,8,9,9,9,9,9,9,9,9,9,9,9,9,...
      10,10,10,10,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11,11,11,11,11,11,...
      12,12,12,12,12,12,12,12,12,12,12,12,13,13,13,13,13,13,13,13,13,13,13,13,...
      14,14,14,14,14,14,14,14,14,14,14,14,15,15,15,15,15,15,15,15,15,15,15,15,...
      16,16,16,16,16,16,16,16,16,16,16,16,17,17,17,17,17,17,17,17,17,17,17,17,...
      18,18,18,18,18,18,18,18,18,18,18,18,19,19,19,19,19,19,19,19,19,19,19,19,...
      20,20,20,20,20,20,20,20,20,20,20,20,21,21,21,21,21,21,21,21,21,21,21,21];

Answer 1

[Azzi Abdelmalek]

C=repmat(1:21,12,1)
C=C(:)'

%or

C=1:21;
C=reshape(C(ones(12,1),:),1,[])

[Stamatis Samaras]

Thanks !

Answer 2

[Andrei Bobrov]

kron(1:21,ones(1,12))

[Stamatis Samaras]

Thank you too!