is(n) = {if(n < 105, return(0)); 
	my(d = digits(1<<n), fr = vector(10), missing);
	for(i = 1, 10, 
		fr[d[i]+1]++;
	); 
	missing = #select(x -> x == 0, fr);
	for(i = 11, #d, 
		fr[d[i-10]+1]--; 
		if(fr[d[i-10]+1] == 0,
			missing++;
		);
		if(fr[d[i]+1]==0,
			missing--;
			if(missing == 0,
				return(1)
			)
		);
		fr[d[i]+1]++;	
	); 0
}