Low power periodic wakeup for creating a clock signal

I want to output a 46Hz clock signal with an 328P. The low power lib with minimum of 15ms sleeping time creates only 26 Hz
How can I speed up the wake up?

// **** INCLUDES *****
#include "LowPower.h"

bool state=false;

void setup()
    pinMode(2, OUTPUT);

void loop() 
    LowPower.powerDown(SLEEP_15MS, ADC_OFF, BOD_OFF);  
    digitalWrite(2, state); 
    state = !state;



That is not possible :( The 15 ms is the minimum for the WatchDog timer and it is not accurate at all ! I think the prescaler is already set to zero for 15 ms.

You can use a normal timer and try to combine it with sleeping. The ATmega328P sleep mode tutorial by Nick Gammon: https://www.gammon.com.au/power