A032920 - OEIS

%I #15 Oct 13 2023 12:20:00

%S 1,3,14,16,40,42,183,185,209,211,521,523,547,549,2380,2382,2406,2408,

%T 2718,2720,2744,2746,6774,6776,6800,6802,7112,7114,7138,7140,30941,

%U 30943,30967,30969,31279,31281,31305,31307,35335,35337

%N Numbers whose set of base-13 digits is {1,3}.

%H Vincenzo Librandi, <a href="/A032920/b032920.txt">Table of n, a(n) for n = 1..1000</a>

%t Flatten[Table[FromDigits[#,13]&/@Tuples[{1,3},n],{n,5}]] (* _Vincenzo Librandi_, Jun 03 2012 *)

%o (Magma) [n: n in [1..36000] | Set(IntegerToSequence(n, 13)) subset {1, 3}]; // _Vincenzo Librandi_, Jun 03 2012

%o (Python)

%o def A032920(n): return (int(bin(m:=n+1)[3:],13)<<1) + (13**(m.bit_length()-1)-1)//12 # _Chai Wah Wu_, Oct 13 2023

%K nonn,base

%O 1,2

%A _Clark Kimberling_