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A242407 Numbers such that in ternary representation all pairs of adjacent digits have sums not greater than 2.

%I A242407 #10 Feb 16 2025 08:33:22
%S A242407 0,1,2,3,4,6,9,10,11,12,13,18,19,20,27,28,29,30,31,33,36,37,38,39,40,
%T A242407 54,55,56,57,58,60,81,82,83,84,85,87,90,91,92,93,94,99,100,101,108,
%U A242407 109,110,111,112,114,117,118,119,120,121,162,163,164,165,166,168
%N A242407 Numbers such that in ternary representation all pairs of adjacent digits have sums not greater than 2.
%C A242407 A242400(a(n)) = 0;
%C A242407 A242399(a(n)) = 4*a(n);
%C A242407 numbers m, such that in ternary arithmetic no carry occurs, when 3*m is added to m.
%H A242407 Reinhard Zumkeller, <a href="/A242407/b242407.txt">Table of n, a(n) for n = 1..10000</a>
%H A242407 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Ternary.html">Ternary.</a>
%H A242407 Wikipedia, <a href="http://en.wikipedia.org/wiki/Ternary_numeral_system">Ternary numeral system</a>
%e A242407 Initial terms and their ternary representations, cf. A007089:
%e A242407 .  0 1 2  3  4  6   9  10  11  12  13  18  19  20   27   28   29   30 ..
%e A242407 .  0 1 2 10 11 20 100 101 102 110 111 200 201 202 1000 1001 1002 1010 ..
%t A242407 Select[Range[0,200],Max[Total/@Partition[IntegerDigits[#, 3],2,1]]<3&] (* _Harvey P. Dale_, Jan 08 2023 *)
%o A242407 (Haskell)
%o A242407 a242407 n = a242407_list !! (n-1)
%o A242407 a242407_list = filter ((== 0) . a242400) [0..]
%Y A242407 Cf. A242408 (complement), A003714, A039691, A007089.
%K A242407 nonn,base
%O A242407 1,3
%A A242407 _Reinhard Zumkeller_, May 13 2014