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URL: https://oeis.org/A350775

⇱ A350775 - OEIS

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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).
2
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, 0, 0, 0, -1, 0, 1, 7, 6, 5, 9, 9, 9, 11, 12, 13, -14, -15, -16, -18, -18, -18, -22, -21, -20, -26, -27, -28, -27, -27, -27, -28, -27, -26, -38, -39, -40, -36, -36
OFFSET
0,6
COMMENTS
This sequence is to balanced ternary what A048735 is to binary, or what A330633 is to decimal.
LINKS
FORMULA
a(n) = 0 iff n belongs to A350776.
EXAMPLE
The first terms, in decimal and in balanced ternary, are:
n a(n) bter(n) bter(a(n))
-- ---- ------- ----------
0 0 0 0
1 0 1 0
2 -1 1T T
3 0 10 0
4 1 11 1
5 -2 1TT T1
6 -3 1T0 T0
7 -4 1T1 TT
8 0 10T 0
9 0 100 0
10 0 101 0
11 2 11T 1T
12 3 110 10
13 4 111 11
PROG
(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)) }
CROSSREFS
KEYWORD
sign,base
AUTHOR
Rémy Sigrist, Jan 15 2022
STATUS
approved