Generating a delayed pulse with one 555 timer upon powering up the circuit

This is a very beginner's question - I apologize if this is some trivial extension of a known practice.

Can I use one 555 timer without any extra transistors/IC to generate a delayed pulse as shown below upon powering up the circuit?

The intended circuit has no buttons or other external triggers. It is activated by being suddenly connected to power (from z-wave smartswitch) and is supposed to:

• after power up, keep output pin low for ~15 seconds


• put output pin to high for ~5 seconds


• finally, put it to low and keep it there forever

This probably can be done easier with two 555 timers but I think that one 555 timer should be able to do it as well. This is also a great learning experience in understanding the mechanics of 555.

Answer

I created the following circuit that seems to be able to accomplish that task with just one 555 and no external triggers.

Explanation of my circuit:

• The left-side attempts to simulate a delayed trigger pulse.
  
  
  
  • R1-C1 is slowly decreasing the voltage from high to low and manipulates the length of time when output will be on LOW (~15 seconds)
  
  
  • R3-C3 is increasing the voltage but slightly slower than R1-C1 so that Trigger voltage dips below 3V but not for long
  
  
  
  


• The right-side is a monostable 555 implementation
  
  
  
  • R4-C4 manipulates the length of time when the output would be on HIGH (~5 seconds)
  
  
  
  
  

^{simulate this circuit – Schematic created using CircuitLab}

Here are the voltage measurements:

Here are the current measurements:

I think this implementation works but is there an easier way to accomplish that?