cp's OEIS Frontend

A350775 The balanced ternary expansion of a(n) is obtained by multiplying adjacent digits in the balanced ternary expansion of n: a(Sum_{k >= 0} t_k * 3^k) = Sum_{k >= 0} t_k * t_{k+1} * 3^k (with -1 <= t_k <= 1 for any k >= 0).

%I A350775 #12 Jan 25 2022 08:51:12
%S A350775 0,0,-1,0,1,-2,-3,-4,0,0,0,2,3,4,-5,-6,-7,-9,-9,-9,-13,-12,-11,1,0,-1,
%T A350775 0,0,0,-1,0,1,7,6,5,9,9,9,11,12,13,-14,-15,-16,-18,-18,-18,-22,-21,
%U A350775 -20,-26,-27,-28,-27,-27,-27,-28,-27,-26,-38,-39,-40,-36,-36
%N A350775 The balanced ternary expansion of a(n) is obtained by multiplying adjacent digits in the balanced ternary expansion of n: a(Sum_{k >= 0} t_k * 3^k) = Sum_{k >= 0} t_k * t_{k+1} * 3^k (with -1 <= t_k <= 1 for any k >= 0).
%C A350775 This sequence is to balanced ternary what A048735 is to binary, or what A330633 is to decimal.
%H A350775 Rémy Sigrist, <a href="/A350775/b350775.txt">Table of n, a(n) for n = 0..9841</a>
%F A350775 a(n) = 0 iff n belongs to A350776.
%e A350775 The first terms, in decimal and in balanced ternary, are:
%e A350775   n   a(n)  bter(n)  bter(a(n))
%e A350775   --  ----  -------  ----------
%e A350775    0     0        0           0
%e A350775    1     0        1           0
%e A350775    2    -1       1T           T
%e A350775    3     0       10           0
%e A350775    4     1       11           1
%e A350775    5    -2      1TT          T1
%e A350775    6    -3      1T0          T0
%e A350775    7    -4      1T1          TT
%e A350775    8     0      10T           0
%e A350775    9     0      100           0
%e A350775   10     0      101           0
%e A350775   11     2      11T          1T
%e A350775   12     3      110          10
%e A350775   13     4      111          11
%o A350775 (PARI) a(n) = { my (v=0, p=0, d); for (x=-1, oo, if (n==0, return (v), d=[0, 1, -1][1+n%3]; v+=p*d*3^x; n=(n-d)/3; p=d)) }
%Y A350775 Cf. A048735, A059095, A330633, A350776.
%K A350775 sign,base
%O A350775 0,6
%A A350775 _Rémy Sigrist_, Jan 15 2022