%I #8 Sep 22 2019 08:40:15
%S 5,9,10,17,70
%N Numbers n such that digit sum of 2^n is less than or equal to n.
%C Probably there are no more terms.
%C Probably 5 and 70 are the only cases when digit sum of 2^n is equal to n. - Tanya Khovanova, Jul 23 2006
%C Probably 1, 2, 5 and 70 are the only cases when digit sum of 2^n is divisible by n. - Zak Seidov, Jul 24 2006
%t Select[Range[80],#>=Total[IntegerDigits[2^#]]&] (* _Harvey P. Dale_, Sep 22 2019 *)
%o (PARI) isok(n) = d = digits(2^n); sum(i=1, #d, d[i]) <= n; \\ _Michel Marcus_, Aug 17 2013
%Y Cf. A001370.
%K nonn,base,fini
%O 1,1
%A _Joshua Zucker_, Jul 24 2006