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%I #21 Sep 08 2022 08:44:51
%S 1,4,10,13,37,40,91,94,118,121,334,337,361,364,820,823,847,850,1063,
%T 1066,1090,1093,3007,3010,3034,3037,3250,3253,3277,3280,7381,7384,
%U 7408,7411,7624,7627,7651,7654,9568,9571,9595,9598
%N Numbers whose set of base-9 digits is {1,4}.
%H Vincenzo Librandi, <a href="/A032821/b032821.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Ar#3-automatic">Index entries for 3-automatic sequences</a>.
%F a(1)=1, a(2)=4; a(n) = 9*a(floor(n/2))+1 for n odd, otherwise a(n) = 9*a(floor((n-1)/2))+4. - _Bruno Berselli_, May 28 2012
%t Select[Range[9600],MemberQ[{{1},{4},{1,4}},Union[IntegerDigits[ #,9]]]&] (* _Harvey P. Dale_, Jul 24 2011 *)
%t Flatten[Table[FromDigits[#,9]&/@Tuples[{1,4},n],{n,5}]] (* _Vincenzo Librandi_, May 28 2012 *)
%o (Magma) [n: n in [1..10000] | Set(IntegerToSequence(n, 9)) subset {1, 4}]; // _Vincenzo Librandi_, May 28 2012
%o (Maxima) a[1]:1$ a[2]:4$ a[n]:= if oddp(n) then 9*a[floor(n/2)]+1 else 9*a[floor((n-1)/2)]+4$ makelist(a[n],n,1,42); /* _Bruno Berselli_, May 28 2012 */
%K nonn,base,easy
%O 1,2
%A _Clark Kimberling_
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