#include <FastLED.h>
#define NUM_LEDS 64
#define DATA_PIN 15
CRGB leds[NUM_LEDS];
void setup() { 
  FastLED.addLeds<WS2812, DATA_PIN, GRB>(leds, NUM_LEDS);  // GRB ordering is typical 
}
void loop() { 
  for(int i=0;i<=31;i++) {
    if(i%2==0) {
      leds[i]    = CRGB::Red;
      leds[63-i] = CRGB::Red;
    } else {
      leds[i]    = CRGB::Lime;
      leds[63-i] = CRGB::Lime;
    }
    FastLED.show(); delay(50);
  }
  for(int i=31;i>=0;i--) {
    if(i%2==0) {
      leds[i]    = CRGB::Blue;
      leds[63-i] = CRGB::Blue;
    } else {
      leds[i]    = CRGB::Yellow;
      leds[63-i] = CRGB::Yellow;
    }
    FastLED.show(); delay(50);
  }
}