How can I create an "irregular" blink?

[Dante12TB]

Hi everybody
I'm new in C++ and in Arduino and I have a question (Sorry if this question may seem too obvius, but for three weeks I tried by myself without any result and aparently I need to ask help to someone). I'm trying for my project to make an "irregular" blink with this library. With the "millis()" metod I did like this:

unsigned long t;
void setup() {
  // put your setup code here, to run once:
pinMode(pin,OUTPUT);
t=millis();
}

void loop() {
  // put your main code here, to run repeatedly:
if(millis()-t>=1000){
  digitalWrite(pin,!digitalRead(pin));
  t=millis();
}
if(millis()-t>=2000){
  digitalWrite(pin,!digitalRead(pin));
  t=millis();
}
}

Practically I want that the delay where the pin is LOW be different by the time where the pin is HIGH. I had already see the #83 discussion but I can't adapt those codes to my application. How could I make this with a program that can dynamically change in the loop()?
Thanks to everybody who will answer me.