A050730 - OEIS

%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