A032914 - OEIS

%I #19 Oct 13 2023 14:03:03

%S 1,3,8,10,22,24,57,59,71,73,155,157,169,171,400,402,414,416,498,500,

%T 512,514,1086,1088,1100,1102,1184,1186,1198,1200,2801,2803,2815,2817,

%U 2899,2901,2913,2915,3487,3489,3501,3503,3585,3587

%N Numbers whose set of base-7 digits is {1,3}.

%H Vincenzo Librandi, <a href="/A032914/b032914.txt">Table of n, a(n) for n = 1..1000</a>

%t Flatten[Table[FromDigits[#,7]&/@Tuples[{1,3},n],{n,5}]] (* _Vincenzo Librandi_, Jun 01 2012 *)

%o (Magma) [n: n in [1..4000] | Set(IntegerToSequence(n, 7)) subset {1, 3}]; // _Vincenzo Librandi_, Jun 01 2012

%o (Python)

%o def A032914(n): return (int(bin(m:=n+1)[3:],7)<<1) + (7**(m.bit_length()-1)-1)//6 # _Chai Wah Wu_, Oct 13 2023

%Y Cf. A007093, A032917.

%K nonn,base

%O 1,2

%A _Clark Kimberling_