OFFSET
1,1
LINKS
Vardan Semerjyan, Voronoi diagram of prime spiral
PROG
(MATLAB)
sz = 201; % Size of the N x N square matrix
mat = spiral(sz); % MATLAB Function
k = 1;
for i =1:sz
for j=1:sz
if isprime(mat(i, j)) % Check if the number is prime
% saving indices of primes
y(k) = i; x(k) = j;
k = k+1;
end
end
end
xy = [x', y'];
[v, c] = voronoin(xy); % Returns Voronoi vertices V and
% the Voronoi cells C
k = 1;
for i = 1:length(c)
szv = size(v(c{i}, 1));
polyN(i) = szv(1);
if polyN(i) == 5
A(k) = mat(y(i), x(i));
k = k+1;
end
end
% Print terms
A = sort(A);
fprintf('A = ');
fprintf('%i, ', A);
% Note that the last terms might not be correct.
% They correspond to the points on the outer edges of the spiral which might be altered when considering a larger spiral.
% Use larger spiral to get more terms
CROSSREFS
KEYWORD
nonn
AUTHOR
Vardan Semerjyan, Apr 28 2015
STATUS
approved