A283800 - OEIS

%I #7 Mar 16 2017 22:34:13

%S 1,3,5,7,9,11,15,17,19,21,23,25,27,29,33,35,43,45,47,49,51,53,55,57,

%T 59,61,63,65,69,71,73,75,77,79,81,83,87,89,95,97,99,101,105,107,113,

%U 127,129,133,135,137,139,141,143,145,147,151,153,155,157,159,161

%N Numbers such that the sum of trits of its balanced ternary representation is 1 or -1.

%H Lei Zhou, <a href="/A283800/b283800.txt">Table of n, a(n) for n = 1..10000</a>

%e 3 = 10 in balanced ternary (bt) notation, 1+0 = 1, so 3 is in the list;

%e ...

%e 11 = 11T in bt notation, 1+1+T = 1, here T represent -1, so 11 is in the list;

%e 13 = 111 in bt notation, 1+1+1 = 3, so 13 is NOT in the list.

%t BTDigits[m_Integer,

%t    g_] :=(*This is to determine digits of a number in balanced \

%t ternary notation.*)

%t   Module[{n = m, d, sign, t = g},

%t    If[n != 0, If[n > 0, sign = 1, sign = -1; n = -n];

%t     d = Ceiling[Log[3, n]]; If[3^d - n <= ((3^d - 1)/2), d++];

%t     While[Length[t] < d, PrependTo[t, 0]];

%t     t[[Length[t] + 1 - d]] = sign;

%t     t = BTDigits[sign*(n - 3^(d - 1)), t]]; t];

%t n = 0; Table[While[n++; g = {}; bt = BTDigits[n, g]; s = Total[bt];

%t   Abs[s] != 1]; n, {i, 1, 61}]

%Y Cf. A065303, A174658.

%K nonn,easy,base

%O 1,2

%A _Lei Zhou_, Mar 16 2017