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A065369
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Replace 3^k with (-3)^k in ternary expansion of n.
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9
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0, 1, 2, -3, -2, -1, -6, -5, -4, 9, 10, 11, 6, 7, 8, 3, 4, 5, 18, 19, 20, 15, 16, 17, 12, 13, 14, -27, -26, -25, -30, -29, -28, -33, -32, -31, -18, -17, -16, -21, -20, -19, -24, -23, -22, -9, -8, -7, -12, -11, -10, -15, -14, -13, -54, -53, -52, -57, -56, -55, -60, -59, -58, -45, -44, -43, -48, -47, -46
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| Base 3 representation for n (in lexicographic order) converted from base -3 to base 10.
Notation: (3)[n](-3)
Fixed point of the morphism 0-> 0,1,2 ; 1-> -3,-2,-1 ; 2-> -6,-5,-4 ; ...; n-> -3n,-3n+1,-3n+2 . - From DELEHAM Philippe, Oct 22 2011.
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FORMULA
| a(n)=Sum_k>=0 {A030341(n,k)*(-3)^k}. - From DELEAM Philippe, Oct 22 2011.
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EXAMPLE
| 15 = +1(9)+2(3)+0(1) -> +1(+9)+2(-3)+0(+1) = +3 = a(15)
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MATHEMATICA
| f[n_Integer, b_Integer] := Block[{l = IntegerDigits[n]}, Sum[l[[ -i]]*(-b)^(i - 1), {i, 1, Length[l]}]]; a = Table[ FromDigits[ IntegerDigits[n, 3]], {n, 0, 80}]; b = {}; Do[b = Append[b, f[a[[n]], 3]], {n, 1, 80}]; b
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CROSSREFS
| Cf. A007089, A053985, A065367, A073785, A073791, A073792, A073793, A073794, A073795, A073796 & A073835.
Sequence in context: A081316 A079893 A113908 * A167772 A077870 A062323
Adjacent sequences: A065366 A065367 A065368 * A065370 A065371 A065372
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KEYWORD
| base,easy,sign
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AUTHOR
| Marc LeBrun (mlb(AT)well.com), Oct 31 2001
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