Tags » Primes

The Andrica's Conjecture

Things should be as simple as possible, but not simpler (Albert Einstein)

Following with conjectures about primes, it is time for Andrica’s conjecture. The great mathematician Leonhard Euler (1707-1783) pointed: “Mathematicians have tried with no success to find some kind of order in the sequence of prime numbers and today we have reasons to believe that this is a mystery that human mind will never understand”.

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Zeiss Compact Primes Super Speed

Currently available:

  • 15mm T2.9
  • 21mm T2.9
  • 28mm T2.1
  • 35mm T1.5 Super Speed
  • 50mm T1.5 Super Speed
  • 85mm T1.5 Super Speed
  • 100mm T2.1
  • 135mm T2.1

We will mix and match any way you want – with a special price just for the Super Speed lenses. 14 more words

Circular Primes (Problem 35)

The number, 197, is called a circular prime because all rotations of the digits: 197, 971, and 719, are themselves prime.

There are thirteen such primes below 100: 2, 3, 5, 7, 11, 13, 17, 31, 37, 71, 73, 79, and 97. 413 more words


Goldbach's Other Conjecture (Problem 46)

It was proposed by Christian Goldbach that every odd composite number can be written as the sum of a prime and twice a square.

9 = 7 + 2×12… 448 more words


Truncatable Primes (Problem 37)

The number 3797 has an interesting property. Being prime itself, it is possible to continuously remove digits from left to right, and remain prime at each stage: 3797, 797, 97, and 7. 557 more words


Generating primes in LaTeX

Inspired by a recent discussion on the wonders of , I started thinking about how easy it would be to generate prime numbers in . Well, unsurprisingly, it was presented as an example by Knuth using trial division in… 148 more words