usagi-pair.js

var month = 0;
var number_of_pairs = 1;
var before_number_of_pairs = 0;
while (month < 12) {
  var b = number_of_pairs;
  number_of_pairs
    = number_of_pairs
    + before_number_of_pairs;
  before_number_of_pairs = b;
  month = month + 1;
  console.log("month : " + month);
  console.log("pairs : " + number_of_pairs);
  console.log("before: " + before_number_of_pairs);
  console.log();
}