|
%I #26 Dec 25 2019 23:12:07
%S 1,2,4,5,7,8,10,11,14,17,20,22,25,28,40,41,44,47,50,52,55,58,70,71,74,
%T 77,80,82,85,88,100,101,104,107,110,140,170,200,202,205,208,220,250,
%U 280,400,401,404,407,410,440,470,500,502,505,508,520,550,580,700
%N Integers such that no nonzero subsequence of decimal representation is divisible by 3.
%C Integers whose decimal representation contains either just one nonzero digit, which == 1 or 2 (mod 3), or just two nonzero digits, which are either both == 1 (mod 3) or both == 2 (mod 3). - _Robert Israel_, Dec 25 2019
%H Robert Israel, <a href="/A325112/b325112.txt">Table of n, a(n) for n = 1..10000</a>
%p F:= proc(d) local i,j,k, g;
%p g:= [1,2,4,5,7,8];
%p op(sort([seq(i*10^(d-1),i=g), seq(seq(seq(i*10^(d-1) + j*10^k, j = select(t -> (t-i) mod 3 = 0, g)),k=0..d-2),i=g)]));
%p end proc:
%p seq(F(d),d=1..4); # _Robert Israel_, Dec 25 2019
%t With[{k = 3}, Select[Range@ 700, NoneTrue[DeleteCases[FromDigits /@ Rest@ Subsequences[IntegerDigits@ #], 0], Mod[#, k] == 0 &] &]] (* _Michael De Vlieger_, Mar 31 2019 *)
%Y Cf. A014261 (for 2), A325113 (for 4), A261189 (for 5), A325114 (for 7).
%Y A261188 is a subsequence.
%K nonn,base
%O 1,2
%A _Jonathan Kal-El Peréz_, Mar 27 2019
|
