Dynamic Repeating Sass Colors

colors.scss

$chartColors: #56c7fa, #f76540, #ffcb05, #62cd9f, #b67baa;
@for $i from 1 through length($chartColors) {
  $chartColors: append($chartColors, darken(nth($chartColors, $i), 25));
}

repeated-colors-full.scss

$chartColors: #56c7fa, #f76540, #ffcb05, #62cd9f, #b67baa;
@for $i from 1 through length($chartColors) {
  $chartColors: append($chartColors, darken(nth($chartColors, $i), 25));
}
$chartColorsLength: length($chartColors);

.color {
  @for $i from 1 through $chartColorsLength {
    &:nth-of-type(#{$chartColorsLength}n+#{$i}) {
      background-color: nth($chartColors, $i);      
    }
  }  
}

repeated-colors.css

.color:nth-of-type(10n+1) {
  background-color: #56c7fa;
}

.color:nth-of-type(10n+2) {
  background-color: #f76540;
}

.color:nth-of-type(10n+3) {
  background-color: #ffcb05;
}

/* ... other 10n+# variations ... */

repeated-colors.scss

$chartColorsLength: length($chartColors);

.color {
  @for $i from 1 through $chartColorsLength {
    &:nth-of-type(#{$chartColorsLength}n+#{$i}) {
      background-color: nth($chartColors, $i);      
    }
  }  
}