Prime Triangle

prime-triangle.py

#!/usr/bin/env python3

import fractions
import sys


def is_prime(n):
    for d in range(2, int(n**0.5)):
        if n % d == 0:
            return False
    return n > 1


def oeis_a054521(n, k):
    return fractions.gcd(n, k) == 1


def gen_tri(n, out=sys.stdout.write):
    for row in range(n):
        for col in range(row + 1):
            ok = False
            for j in range(n):
                if is_prime(n * row * (row + 1) // 2 + col + j *
                            (row + 1) + 1):
                    ok = True
                    break
            out('\033[m' if oeis_a054521(row + 1, col + 1) else '\033[31;1m')
            out('_' if ok else '#')
        out('\033[m\n')


def main():
    gen_tri(int(sys.argv[1]))


if __name__ == '__main__':
    main()

x_output_74.png