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%I #17 May 20 2021 00:23:00
%S 1,3,9,18,90
%N Numbers k such that k divides the sum of digits of 6^k.
%C Conjecture: the sequence is finite, since (sum of the digits of 6^k)/k -> log_10(6)*4.5 ~ 3.50168 as k->infinity (this is also a conjecture). - _Robert Gerbicz_, May 08 2008
%C Next term, if it exists, exceeds 100000. - _Sean A. Irvine_, Apr 05 2010
%e a(1)=3, so 3 divides the sum of digits of 6^3 (i.e., 2 + 1 + 6 = 9).
%Y Cf. A000400, A066002, A175457, A175169, A067862, A067863.
%K hard,nonn,base
%O 1,2
%A _Amarnath Murthy_ and _Shyam Sunder Gupta_, Feb 16 2002
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