Monday 23 January 2012

Monday, 23 January 2012

Today is 23 day of the year.
23 is prime.
23 = 5 + 7 + 11, i.e. the sum of three consecutive primes.
23 is a happy number.
23 is a factorial prime.
23 is a Pillai prime.
23 is a Woodall or Riesel prime.
23 is the fifth Sophie Germain prime.
23 is the fourth safe prime.
23 is a member of the Cunningham chain 2, 5, 11, 23, 47.
23 is a toothpick number.
23 is the lowest score that cannot be achieved with a single dart.
23 is a member of primitive, Pythagorean triple (23, 264, 265).
23 =  1 * 2  +  2 * 3  +  3 * 5, i.e. 1 times the first prime + 2 times the second prime + 3 times the third prime. Apart from the trivial 2 = 1 times the fist prime I cannot see any other prime that can be constructed this way for primes less than or equal to 17389.

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