Edit in JSFiddle

var asSeries = function( start, end, step, func ){
    var i, all = [];
    
    var funcArgs = Array.prototype.slice.call(arguments, 4);
    funcArgs.unshift('0');

    for( i = start; i <= end; i += step ){
        
        funcArgs[0] = i;
        all.push( [ i, func.apply(null, funcArgs) ] );
    }
    
    return all;
}

var bruteComplex = function(x){
    return x * (x - 1) / 2;
}
    
$(function () {
    var chart;
    $(document).ready(function() {
        chart = new Highcharts.Chart({
            chart: {
                renderTo: 'container',
                type: 'line'
            },
            title: {
                text: 'Brute Force Collision Check Counts'
            },
            subtitle: {
                text: 'y = x(x - 1) / 2'
            },
            xAxis: {
                title: {
                    enabled: true,
                    text: 'Entities'
                },
                startOnTick: false,
                endOnTick: false,
                showLastLabel: true
            },
            yAxis: {
                title: {
                    text: 'Collision Checks'
                },
                startOnTick: false
            },
            tooltip: {
                formatter: function() {
                    return 'Entities: ' + this.x +', Checks: '+ this.y;
                }
            },
            legend: {
                enabled: false
            },
            series: [{
                name: '',
                data: asSeries( 0, 100, 1, bruteComplex )
            }]
        });
    });
    
});

<script src="https://code.highcharts.com/highcharts.js"></script>
<script src="https://code.highcharts.com/modules/exporting.js"></script>

<div id="container" style="margin: 0 auto"></div>