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Consecutive Semiprimes (Posted on 2009-09-04) Difficulty: 1 of 5
The smallest semiprime is 4 because it is the product of exactly 2 primes (2 and 2) and the next is 6.

Find the smallest pair of consecutive numbers that are semiprimes.

Find the smallest three consecutive numbers that are semiprimes.

Find the smallest four consecutive numbers that are semiprimes.

Continue up to ten.

See The Solution Submitted by Jer    
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Hemidemisemi... | Comment 1 of 3

Smallest pair: 9 and 10

Smallest triplet 33, 34, 35

Unless I misunderstand the puzzle, there are no longer strings of consecutive numbers all of which are semiprime.  The simplest reason is probably that of any four consecutive numbers, at least one must be divisible by 4; such a number would already have at least two prime factors (2 and 2) and one other, so would not be a semiprime as defined (exactly two prime factors). 


  Posted by ed bottemiller on 2009-09-04 14:58:56
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