summa produkt pussel

sumprod.m

K = 100;
A = zeros(K);
B = zeros(K);
for x = 2:K
  for y = 2:K
    A(x,y) = x + y;
    B(x,y) = x * y;
  end
end

% Eliminate lower diagonal part of B

A = triu(A);
B = triu(B);

% Eliminate all unique numbers from B
% The way that Henrik Holst suggested doing it.

% for b = B(:)'
%   if sum(B(:) == b) == 1
%     B(B(:) == b) = 0;
%   end
% end

% Eliminate all factors of two primes

% for i = 1:K*K
%   if length(factor(B(i))) <= 2
%     B(i) = 0;
%   end
% end
 
% Eliminate all products divisible by a prime less than 541
% NOTE: This is all products.

% p = primes(541);
% 
% for i = 1:K*K
%   if any(ismember(factor(B(i)), p))
%     B(i) = 0;
%   end
% end