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Narcissus Prime in Python

· Web Dev Zone

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I’ve been looking back on some of my blog posts that included Mathematica code to see whether I could rewrite them using Python. For example, I rewrote my code for finding sonnet primes in Python a few days ago. Next I wanted to try testing the Narcissus prime.

Futility closet describes the Narcissus prime as follows:

Repeat the string 1808010808 1560 times, and tack on a 1 the end. The resulting 15601-digit number is prime, and because it’s a palindrome made up of the digits 1, 8, and 0, it remains prime when read backward, upside down, or in a mirror.

My Mathematica code for verifying this claim is posted here. Here’s Python code to do the same thing:

    from sympy.ntheory import isprime
    isprime(int("1808010808"*1560 + "1"))

This does indeed return True. However, the Mathematica code ran for about 2 minutes and the SymPy code took 17.5 hours, about 500 times longer.

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