Select Code to Download

  1
  2  3
  4  5  6
  7  8  9 10
 11 12 13 14 15

   1
   2   3
...
  79  80  81  82  83  84  85  86  87  88  89  90  91
  92  93  94  95  96  97  98  99 100 101 102 103 104 105
 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120

$n=length($a*($a+1)/2)+1;map{map{printf"%${n}d",++$k}1..$_;print"\n"}1
+..$a;