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Message: [QUOTE="Zed Lopez, post: 4495848"] I was impressed when I started going through 1..1000 in under 15 seconds, so this is much slower than others report. I'm just going to tell myself you all have much faster computers, and go to bed. require 'set' class Subsets def initialize(set, start) @set = set.to_a.uniq.sort @num_elements = start - 1 @map = {} @set.each_with_index {|k, v| @map[k] = v+1} end # returns each subset, in turn. Returns nil when there are no more def succ if @combo == nil or @combo == @set[-@num_elements..-1] return nil if (@num_elements +=1) > @set.length @combo = @set[0,@num_elements] else index = (1..@num_elements).find {|i| @combo[-i] < @set[-i]} @combo[-index, index] = @set[@map[@combo[-index]], index] end @combo end def find while(x = succ) break if yield x end x end end class Integer def proper_divisors return [] if self < 2 div = Set.new [1] 2.upto(Math.sqrt(Float.induced_from(self)).to_i) {|i| quotient, modulus = self.divmod(i) div.merge([i,quotient]) if modulus.zero? } div.to_a.sort end def abundant? self > 11 and [0].concat(proper_divisors).inject {|sum,n| sum += n} end def semiperfect? return nil if self < 6 subsets = Subsets.new(proper_divisors, 2) subsets.find {|subset| [0].concat(subset).inject {|sum,n| sum += n} == self } end def weird? self > 69 and abundant? and not semiperfect? end end n = gets.strip exit if n =~ /\D/ or n !~ /[^0]/ p (1..n.to_i).find_all {|i| i.weird? } [/QUOTE]