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A117771
Numbers n such that digit sum of 2^n is less than or equal to n.
0
5, 9, 10, 17, 70
OFFSET
1,1
COMMENTS
Probably there are no more terms.
Probably 5 and 70 are the only cases when digit sum of 2^n is equal to n. - Tanya Khovanova, Jul 23 2006
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
MATHEMATICA
Select[Range[80], #>=Total[IntegerDigits[2^#]]&] (* Harvey P. Dale, Sep 22 2019 *)
PROG
(PARI) isok(n) = d = digits(2^n); sum(i=1, #d, d[i]) <= n; \\ Michel Marcus, Aug 17 2013
CROSSREFS
Cf. A001370.
Sequence in context: A136318 A242139 A216765 * A227853 A275240 A175437
KEYWORD
nonn,base,fini
AUTHOR
Joshua Zucker, Jul 24 2006
STATUS
approved