This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A169965 #34 Oct 26 2024 14:45:34
%S A169965 0,2,20,22,200,202,220,222,2000,2002,2020,2022,2200,2202,2220,2222,
%T A169965 20000,20002,20020,20022,20200,20202,20220,20222,22000,22002,22020,
%U A169965 22022,22200,22202,22220,22222,200000,200002,200020,200022,200200,200202,200220,200222
%N A169965 Numbers whose decimal expansion contains only 0's and 2's.
%H A169965 Reinhard Zumkeller, <a href="/A169965/b169965.txt">Table of n, a(n) for n = 1..10000</a>
%H A169965 <a href="/index/Ca#CARRYLESS">Index entries for sequences related to carryless arithmetic</a>
%F A169965 a(n+1) = Sum_{k>=0} A030308(n,k)*A093136(k+1). - _Philippe Deléham_, Oct 16 2011
%F A169965 a(n) = 2 * A007088(n-1).
%t A169965 Map[FromDigits,Tuples[{0,2},6]] (* _Paolo Xausa_, Oct 30 2023 *)
%o A169965 (PARI) print1(0);for(d=1,5,for(n=2^(d-1),2^d-1,print1(", ");forstep(i=d-1,0,-1,print1((n>>i)%2*2)))) \\ _Charles R Greathouse IV_, Nov 16 2011
%o A169965 (PARI) lista(N) = vector(N, i, fromdigits(binary(i-1)*2)); \\ _Ruud H.G. van Tol_, Oct 26 2024
%o A169965 (Haskell)
%o A169965 a169965 n = a169965_list !! (n-1)
%o A169965 a169965_list = map (* 2) a007088_list
%o A169965 -- _Reinhard Zumkeller_, Jan 10 2012
%Y A169965 Cf. A007088, A014263, A169964, A169966, A169967.
%Y A169965 Cf. A078241, A204093, A204094, A204095, A097256.
%K A169965 nonn,base,easy
%O A169965 1,2
%A A169965 _N. J. A. Sloane_, Aug 07 2010