Problem 60943. Ulam primes second formula

Historical context
The polish-american mathematician Stanislaw Ulam found the formula to give some prime numbers not given neither by Euler's formula neither by its own first formula.
Problem statement
For a given integer m, m >= 59, list the Ulam prime numbers less or equal to m in a vector up. Also compute their frequency / ratio f compare to all the primes in the same range. If m is not a positive integer greater or equal to 59, your function should return up = [] and f = 0.
Examples (check the tests for more)
  • If m = 59 then up = 59 and f = 1 since 59 = P(0) and it is the only prime number m greater or equal and less or equal to 59;
  • If m = 200 then up = [59, 67, 83, 107, 139, 179] and f = 6/30 since 59 = P(0), 67 = P(1), 83 = P(2), 107 = P(3), 139 = P(4), 179 = P(5), and there are in total 30 prime numbers in the range [59; 200] ;
  • If m = 23 then up = [] and f = 0;
Tip
here.
Fobidden functions
  • regexp
  • assignin
  • str2num
See also
Solve

Solution Stats

69.57% Correct | 30.43% Incorrect
Last Solution submitted on Oct 06, 2025

Problem Comments

Solution Comments

Show comments

Problem Recent Solvers14

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!