upto(n) = {my(l=List(), res = List()); n += 2; 
for(i=1, sqrtnint(n,3), 
	for(j=1, sqrtnint(n - i^3, 2),
			listput(l,i^3+j^2)
	)
);
listsort(l,1);
for(i = 1, #l - 2, 
	if(l[i] + 2 == l[i+2],
		listput(res, l[i]);
	)
); res
}