#include <FastLED.h>

CRGBArray<256> leds;

uint8_t colr[] = {255, 128, 64};
uint8_t colg[] = {128, 64, 255};
uint8_t colb[] = {64, 255, 128};

void setup() {
  FastLED.addLeds<WS2812B, 2, GRB>(leds, leds.size());
}

void loop() {
  static uint8_t offset = 0;
  uint8_t pos = offset++;
  for (int x = 0; x < leds.size(); x++) {
    pos = ++pos % 3;
    leds[x].setRGB(colr[pos],colg[pos],colb[pos]);
  }
  FastLED.delay(100);
}