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Search: id:A161825
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| A161825 |
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a(n) = GCD of n and {the number made by reversing the order of the digits of n written in binary}. |
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+0
1
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| 1, 1, 3, 1, 5, 3, 7, 1, 9, 5, 1, 3, 1, 7, 15, 1, 17, 9, 1, 5, 21, 1, 1, 3, 1, 1, 27, 7, 1, 15, 31, 1, 33, 17, 7, 9, 1, 1, 3, 5, 1, 21, 1, 1, 45, 1, 1, 3, 7, 1, 51, 1, 1, 27, 1, 7, 3, 1, 1, 15, 1, 31, 63, 1, 65, 33, 1, 17, 3, 7, 1, 9, 73, 1, 15, 1, 1, 3, 1, 5, 3, 1, 1, 21, 85, 1, 3, 1, 1, 45, 1, 1, 93, 1
(list; graph; listen)
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OFFSET
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1,3
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EXAMPLE
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70 in binary is 1000110. Reversing this (and ignoring the leading 0), we have 110001, which is 49 in decimal. Therefore a(70) = GCD(70,49) = 7.
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MAPLE
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A030101 := proc(n) local bdgs; bdgs := convert(n, base, 2) ; add( op(-i, bdgs)*2^(i-1), i=1..nops(bdgs)) ; end: A161825 := proc(n) gcd(A030101(n), n) ; end: seq(A161825(n), n=1..100) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 04 2009]
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CROSSREFS
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A030101
Sequence in context: A116528 A081431 A053641 this_sequence A099551 A036233 A145799
Adjacent sequences: A161822 A161823 A161824 this_sequence A161826 A161827 A161828
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KEYWORD
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base,nonn
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AUTHOR
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Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Jun 20 2009
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EXTENSIONS
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Example corrected by Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Jun 21 2009
a(4) corrected and sequence extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 04 2009
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