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A073791
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Replace 4^k with (-4)^k in base 4 expansion of n.
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9
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0, 1, 2, 3, -4, -3, -2, -1, -8, -7, -6, -5, -12, -11, -10, -9, 16, 17, 18, 19, 12, 13, 14, 15, 8, 9, 10, 11, 4, 5, 6, 7, 32, 33, 34, 35, 28, 29, 30, 31, 24, 25, 26, 27, 20, 21, 22, 23, 48, 49, 50, 51, 44, 45, 46, 47, 40, 41, 42, 43, 36, 37, 38, 39, -64, -63, -62, -61, -68, -67, -66, -65, -72, -71, -70, -69
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OFFSET
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0,3
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COMMENTS
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Base 4 representation for n converted from base -4 to base 10.
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LINKS
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FORMULA
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a(4*k+m) = -4*a(k)+m for 0 <= m < 4. - Chai Wah Wu, Jan 16 2020
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MATHEMATICA
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f[n_Integer, b_Integer] := Block[{l = IntegerDigits[n]}, Sum[l[[ -i]]*(-b)^(i - 1), {i, 1, Length[l]}]]; a = Table[ FromDigits[ IntegerDigits[n, 4]], {n, 0, 80}]; b = {}; Do[b = Append[b, f[a[[n]], 4]], {n, 1, 80}]; b
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PROG
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(PARI) a(n) = subst(Pol(digits(n, 4)), x, -4); \\ Michel Marcus, Jan 30 2019
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CROSSREFS
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KEYWORD
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base,easy,sign
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AUTHOR
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STATUS
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approved
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