<?php
    $array = array('1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z');
    $find = rand(1,61);
    $no_1 = $array[$find];
    $find2 = rand(1,61);
    $no_2 = $array[$find2];
    $find3 = rand(1,61);
    $no_3 = $array[$find3];
    $find4 = rand(1,61);
    $no_4 = $array[$find4];
    $find5 = rand(1,61);
    $no_5 = $array[$find5];
    $find6 = rand(1,61);
    $no_6 = $array[$find6];

    $CAPTCHA = $no_1 . $no_2 . $no_3 . $no_4 . $no_5 . $no_6;
    echo $CAPTCHA;
    ?>