@grid-tablet-columns: 4;

.for(@i: 1) when (@i <= (@grid-tablet-columns - 1)) {
  .mdl-cell--@{i}-offset,
  .mdl-cell--@{i}-offset-tablet.mdl-cell--@{i}-offset-tablet {
    .offset-size(@i, @grid-tablet-columns);
  }
  .for((@i + 1));
}
.for();

.for(@i: 1) when (@i < (@grid-tablet-columns)) {
  .mdl-cell--@{i}-offset,
  .mdl-cell--@{i}-offset-tablet.mdl-cell--@{i}-offset-tablet {
    .offset-size(@i, @grid-tablet-columns);
  }
  .for((@i + 1));
}
.for();

.bar {
  content: "rows: @{grid-tablet-columns}"
}