Between posting and coming back to check, I found that the following works. Obviously, the answer from Stephen is a better way, but thought I would post it anyway:
aDays(8760,1) =NaN;
i=1;
j=24;
m=1;
while m<366
aDays(i:j,1)=m;
i=i+24;
j=j+24;
m=m+1;
end