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A132140 Numbers containing no zeros in ternary representation and with an initial 1.

%I A132140 #15 Apr 06 2019 23:13:26
%S A132140 1,4,5,13,14,16,17,40,41,43,44,49,50,52,53,121,122,124,125,130,131,
%T A132140 133,134,148,149,151,152,157,158,160,161,364,365,367,368,373,374,376,
%U A132140 377,391,392,394,395,400,401,403,404,445,446,448,449,454,455,457,458,472
%N A132140 Numbers containing no zeros in ternary representation and with an initial 1.
%C A132140 Intersection of A032924 and A132141;
%C A132140 A132138(A132139(a(n))) = 1.
%H A132140 R. Zumkeller, <a href="/A132140/b132140.txt">Table of n, a(n) for n = 1..10000</a>
%H A132140 <a href="/index/Ar#3-automatic">Index entries for 3-automatic sequences</a>.
%e A132140 14 is in the sequence because its ternary representation is 112;
%e A132140 15 is not in the sequence because its ternary representation is 120.
%p A132140 a:=proc(n) local nn, L: nn:=convert(n,base,3): L:=nops(nn): if nn[L]=1 and 0 < product(nn[j],j=1..L) then n else end if end proc: seq(a(n),n=1..500); # _Emeric Deutsch_, Sep 09 2007
%t A132140 Flatten[Table[FromDigits[Join[{1},#],3]&/@Tuples[{1,2},n],{n,0,5}]] (* _Harvey P. Dale_, Jan 28 2015 *)
%o A132140 (Haskell)
%o A132140 a132140 n = a132140_list !! (n-1)
%o A132140 a132140_list = filter f [1..] where
%o A132140    f x = x < 3 && x == 1 || t > 0 && f x' where (x', t) = divMod x 3
%o A132140 -- _Reinhard Zumkeller_, Feb 06 2015
%Y A132140 Cf. A032924, A132141, A132138, A132139, A007089.
%K A132140 nonn,base,easy
%O A132140 1,2
%A A132140 _Reinhard Zumkeller_, Aug 20 2007