JSFiddle - React, Tailwind, and code Playground

HTML

<form>
    Plage 1
    min<input type="text" name="r1min" value="1"/>
    max<input type="text" name="r1max" value="16"/>
    <br/>
    Plage 2
    min<input type="text" name="r2min" value="2"/>
    max<input type="text" name="r2max" value="17"/>
    <br/>
    Plage 3
    min<input type="text" name="r3min" value="3"/>
    max<input type="text" name="r3max" value="18"/>
    <br/>
       Plage 4
    min<input type="text" name="r3min" value="4"/>
    max<input type="text" name="r3max" value="19"/>
    <br/>
       Plage 5
    min<input type="text" name="r3min" value="5"/>
    max<input type="text" name="r3max" value="20"/>
    <br/>
       Plage 6
    min<input type="text" name="r3min" value="1"/>
    max<input type="text" name="r3max" value="4"/>
    <br/>
       Plage 7
    min<input type="text" name="r3min" value="2"/>
    max<input type="text" name="r3max" value="5"/>
    <br/>
    
    <input type="submit" value="go"/>
    </form>
    <hr/>
    <div id="output"></div>

JavaScript

function getCombis(r1,r2,r3,r4,r5,r6,r7){
    var combis = [];
    for(var i = r1[0]; i<=r1[1];++i){
        for(var j = Math.max(i+1, r2[0]); j<=r2[1]; ++j){
            for(var k = Math.max(j+1, r3[0]); k<=r3[1]; ++k){
             		for(var l = Math.max(k+1, r4[0]); l<=r4[1]; ++l){
            				for(var m = Math.max(l+1, r5[0]); m<=r5[1]; ++m){
           						 for(var n = Math.max(m+1, r6[0]); n<=r6[1]; ++n){
          							  for(var o = Math.max(n+1, r7[0]); o<=r7[1]; ++o){
      
                combis.push([i,j,k,l,m,n,o>9?String.fromCharCode(55+o):o].join(''))
              				 		 }
              		  		}
              	  	}
                }
            }
        }
    }
    return combis;
}

var f = document.getElementsByTagName('form')[0];
    var outputNode = document.getElementById('output');
    f.onsubmit = function(e){
        try{
            ['r1','r2','r3','r4','r5','r6','r7'].forEach(x=>{
                window[x] = [parseInt(this[x+'min'].value, 50), parseInt(this[x+'max'].value, 50)];
            }, this)
            var combis = getCombis(r1,r2,r3,r4,r5,r6,r7)
            outputNode.innerHTML = combis.join('<br/>')+'<br/>total combis '+combis.length;
        }catch(e){
            console.log('e :' , e)
        }
        return false;
    }