goldback(n)

function goldback(n)
%goldbach conjucture verification
tic
clc
if nargin==0
    n = 50;
end
if n<2 || (rem(n,2)==1)
    disp('ENTER +VE EVEN NUMBER GREATER THAN 2')
    return
end
p = primes(n);
z1 = cell(1,length(p));
for k = 1:length(p)
    x = n-p(k);
    t = and(isprime(x),isprime(p(k)));
    if t==1;
        m = p(k);
        z = {m,x};
        z1(k) = {z};
    else
        z1(k) = {0};
    end
end
for k = length(z1):-1:1
    q = z1{k};
    if isscalar(q)
        z1(k) = [];
    end
end
k = length(z1);
k3 = round(k/2);
if rem(k,2)==0
    z1(k3+1:k) = [];
else
    z1((k3+1):k) = [];
end
disp(' ')
fprintf('%d can be formed by combination\nof 2 prime numbers as follow:\n',n)
k = length(z1);
for k1 = 1:k;
    x = z1{k1};
    a = x{1};
    b = x{2};
    fprintf('%d & %d\n',a,b)
end
fprintf('Total possible combinations\nare %d whose sum is = %d\n',k,n)
disp(' ')
toc;
end