%I
%S 22,47,92,157,187,188,192,552,558,577,707,772,922,2522,8338,17177,
%T 66888,575757,929522,1717177,8888588
%N Numbers n such that the smallest exponent k for n and n^k to have common digits is 4.
%e 22^2=484 and 22^3=10648 have no digits in common with 22, but 22^4=234256 has some, so 22 is in the sequence.
%o (PARI) a253600(n) = {sd = Set(vecsort(digits(n))); k=2; while (#setintersect(sd, Set(vecsort(digits(n^k)))) == 0, k++); k;}
%o isok(n) = a253600(n) == 4;
%Y Cf. A029790, A103173, A189056, A253600, A253601.
%K nonn,base,more
%O 1,1
%A _Michel Marcus_, Jan 05 2015
