|
%I #12 Jan 25 2022 08:51:12
%S 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 0,0,0,-1,0,1,7,6,5,9,9,9,11,12,13,-14,-15,-16,-18,-18,-18,-22,-21,
%U -20,-26,-27,-28,-27,-27,-27,-28,-27,-26,-38,-39,-40,-36,-36
%N 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 This sequence is to balanced ternary what A048735 is to binary, or what A330633 is to decimal.
%H Rémy Sigrist, <a href="/A350775/b350775.txt">Table of n, a(n) for n = 0..9841</a>
%F a(n) = 0 iff n belongs to A350776.
%e The first terms, in decimal and in balanced ternary, are:
%e n a(n) bter(n) bter(a(n))
%e -- ---- ------- ----------
%e 0 0 0 0
%e 1 0 1 0
%e 2 -1 1T T
%e 3 0 10 0
%e 4 1 11 1
%e 5 -2 1TT T1
%e 6 -3 1T0 T0
%e 7 -4 1T1 TT
%e 8 0 10T 0
%e 9 0 100 0
%e 10 0 101 0
%e 11 2 11T 1T
%e 12 3 110 10
%e 13 4 111 11
%o (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 Cf. A048735, A059095, A330633, A350776.
%K sign,base
%O 0,6
%A _Rémy Sigrist_, Jan 15 2022
|
