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A060585
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Write n in base 3, then (working from left to right) if the k-th digit of n is not equal to the digit to its left then the k-th digit of a(n) is 1, otherwise it is 0, and finally read the result as a base-2 number.
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2
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0, 1, 1, 3, 2, 3, 3, 3, 2, 6, 7, 7, 5, 4, 5, 7, 7, 6, 6, 7, 7, 7, 6, 7, 5, 5, 4, 12, 13, 13, 15, 14, 15, 15, 15, 14, 10, 11, 11, 9, 8, 9, 11, 11, 10, 14, 15, 15, 15, 14, 15, 13, 13, 12, 12, 13, 13, 15, 14, 15, 15, 15, 14, 14, 15, 15, 13, 12, 13, 15, 15, 14, 10, 11, 11, 11, 10, 11, 9, 9
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OFFSET
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0,4
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COMMENTS
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A ternary-to-binary map.
Each k appears A001316(k) times in the sequence.
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LINKS
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FORMULA
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EXAMPLE
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a(76) = 10 since 76 = 2211_3 and looking for changing digits produces 1010 which, read as if in binary, is 10.
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PROG
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(PARI) a(n) = my(v=digits(n, 3)); if(#v, forstep(k=#v, 2, -1, v[k]=(v[k]!=v[k-1])); v[1]=1); fromdigits(v, 2); \\ Kevin Ryde, Apr 15 2021
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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Definition rewritten by Editors of OEIS, Apr 15 2021.
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STATUS
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approved
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