% MS-A050x L1B example 2
%
% argument: n = number of positions (default=4)
%
function l1b2sequences(n)

    if nargin<1, n=4; end
    if n==1, error('sorry, this code does not work for n=1'); end
    
    fprintf('all possible 01-sequences of length %d:\n', n)
    totalseq = 0;
    
    for k=0:n
        fprintf('--------------------------------------\n');
        CC = nchoosek(1:n, k);
        nseq = size(CC,1);
        totalseq = totalseq + nseq;
        
        for i=1:nseq
            C = CC(i,:);
            x = zeros(1,n);
            x(C) = 1;
            fprintf(' %d', x);
            if i == nseq
                fprintf('   %4d sequences that have %d ones', nseq, k);
            end
            fprintf('\n');
        end
    end
    
    fprintf('--------------------------------------\n');
    fprintf(repmat('  ', 1, n));
    fprintf('   %4d = 2^%d sequences total\n', totalseq, n);
end