gistfile1.rb

def decimals(number)
  number.to_s.split(//).size
end

def even?(number)
  decimals(number) % 2 == 0
end

def split(number)
  str = number.to_s
  half = str.split(//).size / 2
  first = str[0..half-1].to_i
  later = str[half..-1].to_i
  return first, later
end

def adjoin?(a, b)
  (a - b).abs == 1
end

list = []
number = 0
while list.size < 21
  number += 1
  square = number * number
  next unless even?(square) && adjoin?(*split(square))
  list << square
  puts "%2d: #{square} (%d^2)" % [list.size, number]
end