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A161980 a(n) = the smallest positive multiple of n containing {the string made by reversing the order of the binary digits of n, and removing leading 0's} as a substring when a(n) is written in binary. 2

%I #7 Mar 11 2014 01:32:34

%S 1,2,3,4,5,6,7,8,9,10,55,12,91,14,15,16,17,18,57,20,21,110,253,24,275,

%T 182,27,28,87,30,31,32,33,34,455,36,333,114,741,40,1189,42,215,220,45,

%U 506,893,48,931,550,51,364,689,54,495,56,627,174,885,60,1403,62,63,64

%N a(n) = the smallest positive multiple of n containing {the string made by reversing the order of the binary digits of n, and removing leading 0's} as a substring when a(n) is written in binary.

%e 13 in binary is 1101, which reversed is 1011. a(13) = the positive multiple of 13 that contains the string 1011 as a substring in its binary representation. a(13) therefore equals 91 = 7*13, which is 1011011 in binary. (Binary 91 actually contains the substring 1011 twice.)

%Y Cf. A030101, A161979.

%K base,nonn

%O 1,2

%A _Leroy Quet_, Jun 23 2009

%E Extended by _Ray Chandler_, Mar 12 2010

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Last modified April 23 03:30 EDT 2024. Contains 371906 sequences. (Running on oeis4.)