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A158877
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Definition of a(n): in base-n arithmetic a(n) is the smallest positive integer that is doubled when its least significant digit is moved to become the most significant digit.
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2
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OFFSET
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3,1
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COMMENTS
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The problem has no solution in base 2, so sequence begins with the base-3 solution. The idea was suggested by a NY Times article (Sunday Magazine of Mar 29, 2009) -- in which Freeman Dyson is said to have solved the base-10 question almost instantaneously when it was posed to him -- and by the ensuing math-fun discussion.
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LINKS
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Table of n, a(n) for n=3..12.
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EXAMPLE
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For n = 5, the smallest positive integer whose base-5 representation doubles when the rightmost digit is moved to become the leftmost digit is 8 = 13_5; 31_5 = 16.
For n = 8, the smallest positive integer whose base-8 representation doubles when the rightmost digit is moved to become the leftmost digit is 21 = 25_8; 52_8 = 42. - Robert Tanniru, Aug 09 2022
For n = 13, the number can't be represented in this list as it would be 27A5 in base 13.
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CROSSREFS
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See A087502 (which is the main entry for this sequence) for these numbers written in base 10. Cf. A023094, A159774.
Sequence in context: A178349 A291962 A094946 * A159774 A072140 A080467
Adjacent sequences: A158874 A158875 A158876 * A158878 A158879 A158880
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KEYWORD
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nonn,base
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AUTHOR
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Daniel Asimov (asimov(AT)msri.org), Mar 28 2009
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EXTENSIONS
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a(5) corrected by William A. Hoffman III (whoff(AT)robill.com), Apr 19 2009
a(8) corrected by Robert Tanniru, Aug 09 2022
a(11)-a(12) from Robert Tanniru, Aug 11 2022, using A087502
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STATUS
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approved
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