19 lines
409 B
Ruby
19 lines
409 B
Ruby
require 'prime'
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emirp = Enumerator.new do |y|
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Prime.each do |prime|
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rev = prime.to_s.reverse.to_i
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y << prime if rev.prime? and rev != prime
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end
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end
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puts "First 20 emirps:", emirp.first(20).join(" ")
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puts "Emirps between 7,700 and 8,000:"
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emirp.with_index(1) do |prime,i|
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print "#{prime} " if (7700..8000).cover?(prime)
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if i==10000
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puts "", "10,000th emirp:", prime
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break
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end
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end
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