cp's OEIS Frontend

A242408 Numbers such that in ternary representation at least one pair of adjacent digits has a sum greater than 2.

%I A242408 #8 Feb 16 2025 08:33:22
%S A242408 5,7,8,14,15,16,17,21,22,23,24,25,26,32,34,35,41,42,43,44,45,46,47,48,
%T A242408 49,50,51,52,53,59,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,
%U A242408 78,79,80,86,88,89,95,96,97,98,102,103,104,105,106,107,113
%N A242408 Numbers such that in ternary representation at least one pair of adjacent digits has a sum greater than 2.
%C A242408 A242400(a(n)) > 0;
%C A242408 A242399(a(n)) < 4*a(n).
%H A242408 Reinhard Zumkeller, <a href="/A242408/b242408.txt">Table of n, a(n) for n = 1..10000</a>
%H A242408 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Ternary.html">Ternary.</a>
%H A242408 Wikipedia, <a href="http://en.wikipedia.org/wiki/Ternary_numeral_system">Ternary numeral system</a>
%e A242408 Initial terms and their ternary representations, cf. A007089:
%e A242408 .  5  7  8  14  15  16  17  21  22  23  24  25  26   32   34   35   41 ..
%e A242408 . 12 21 22 112 120 121 122 210 211 212 220 221 222 1012 1021 1022 1112 ..
%t A242408 Select[Range[200],Max[Total/@Partition[IntegerDigits[#,3],2,1]]>2&] (* _Harvey P. Dale_, Feb 12 2016 *)
%o A242408 (Haskell)
%o A242408 a242408 n = a242408_list !! (n-1)
%o A242408 a242408_list = filter ((> 0) . a242400) [0..]
%Y A242408 Cf. A242407 (complement), A004780.
%K A242408 nonn,base
%O A242408 1,1
%A A242408 _Reinhard Zumkeller_, May 13 2014