var seeds = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16],

    num_rounds = Math.log(seeds.length)/Math.log(2);

​

//2-dimensional array, each subarray holds the seeds active in that round, in order of matches played

//example: seeds in first match of 2nd round are: seed_round[1][0] & seed_round[1][1]

var seed_rounds=[];

//messy here, just creates empty arrays inside seed_round

for (var i=0;i<num_rounds;i++) {

  seed_rounds[i]=[];  

}

//assuming no upsets in the bracket, 1st and 2nd seeds should be in the final match

seed_rounds[num_rounds] = [1,2];

​

//for each round in the bracket

for (var r=num_rounds;r>0;r--) {

  var round=seed_rounds[r];

  var feed_round=seed_rounds[r-1];

  //for each seed in the round, work out the who they defeated in the previous round, storing the resil

  for (var m=0;m<round.length;m++) {

    var num_teams_in_round = round.length*2;

    //feeder match seed A = current match seed "m"

    feed_round[m*2]=round[m];

    //feeder match seed B = # teams in feeder round plus 1 minus current match seed "m" 

    feed_round[(m*2)+1]=num_teams_in_round+1-round[m];

  }

}

console.log("seeds:"+seed_rounds[1]);