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The number of minesweepers that supported the DDay convoys in World War II. The smallest prime such that the product of its digits is equal to 2 times the number of digits times the sum of digits. [Russo] The largest threedigit prime which remains prime when 2 is added to any of its digits, i.e., 547, 367, and 349, are primes. [Opao] Strobogrammatic primes on a calculator do not contain the digits 3, 4, or 7. The fictitional street number of Dracula's London house (347 Piccadilly) according to Leslie S. Klinger's book The New Annotated Dracula. [Post] The smallest Friedman emirp. [Beedassy] The largest prime factor of 1!+2!+3!+4!+5!+6!+7!+8!+9!. [Upadhyay] There are exactly 347 even digits before the 347th odd digit of . (347 is the smallest prime making the previous statement true.) [Keith] 2^2*3^3*7^7*347^3471 is the largest nontitanic prime of form 2^2*3^3*7^7*347^347*...* a(n1)^a(n1)*a(n)^a(n)1, where n, a(n) and 2^2*3^3*...*a(n)^a(n) – 1 are prime, a(n)>a(n1), and a(n) is minimal. Note that the previous such primes are: a(1) = 2^21 = 3, a(2) = 2^2*3^31 = 107, a(3) = 2^2*3^3*7^7*1 = 88942643. [Loungrides] Number of chess games that end in checkmate after a half dozen plies.
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