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A140268
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a(n) = negative integer -n presented in balanced ternary system.
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2
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2, 21, 20, 22, 211, 210, 212, 201, 200, 202, 221, 220, 222, 2111, 2110, 2112, 2101, 2100, 2102, 2121, 2120, 2122, 2011, 2010, 2012, 2001, 2000, 2002, 2021, 2020, 2022, 2211, 2210, 2212, 2201, 2200, 2202, 2221, 2220, 2222, 21111, 21110, 21112
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OFFSET
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1,1
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COMMENTS
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Sequence A117968 in ternary. (See there for more references.)
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LINKS
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EXAMPLE
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For example a(2) = 21, as -2 = -1*3 + 1*1.
Similarly, a(19) = 2102, as -19 = -1*27 + 1*9 + 0*3 + -1*1.
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PROG
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(Python)
from sympy.ntheory.factor_ import digits
def a117968(n):
if n==1: return 2
if n%3==0: return 3*a117968(n/3)
elif n%3==1: return 3*a117968((n - 1)/3) + 2
else: return 3*a117968((n + 1)/3) + 1
def a(n): return int("".join(map(str, digits(a117968(n), 3)[1:]))) # Indranil Ghosh, Jun 06 2017
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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