function B = listIndBlocks1D(J,N)

    n = log2(N) ;
    
    Nb = J + 1 ;
    B = cell(1, Nb) ;
    
    B{1} = 1:2^(n-J) ;
    
    index = 2 ;
    for j=J:-1:1 
       B{index} = 2^(n-j)+1 : 2^(n-(j-1));
       index = index + 1 ;
    end
end