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%I #10 Sep 16 2024 17:13:57
%S 0,1,2,3,4,5,7,8,9,11,12,13,21,33
%N Decimal expansion of 9^n contains no pair of consecutive equal digits (probably finite).
%e 9^33 = 30903154382632612361920641803529.
%p q:= n-> (s-> andmap(i-> s[i]<>s[i+1], [$1..length(s)-1]))(""||(9^n)):
%p select(q, [$0..200])[]; # _Alois P. Heinz_, Mar 07 2024
%t Select[Range[0,350],FreeQ[Differences[IntegerDigits[9^#]],0]&] (* _Harvey P. Dale_, Sep 16 2024 *)
%Y Cf. A030705, A046267, A046275.
%K nonn,base
%O 0,3
%A _Patrick De Geest_, Sep 15 1999