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Search: id:A141708
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| A141708 |
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Least positive multiple of 2n-1 which is palindromic in base 2. |
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+0
3
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| 1, 3, 5, 7, 9, 33, 65, 15, 17, 513, 21, 2047, 325, 27, 1421, 31, 33, 455, 2553, 195, 1025, 129, 45, 4841, 1421, 51, 3339, 165, 513, 6077, 427, 63, 65, 1273, 2553, 10437, 73, 975, 231, 1501, 891, 3735, 85, 3219, 2047, 273, 93, 2565, 5917, 99, 23533, 4841, 1365, 107
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Even numbers cannot be palindromic in base 2 (unless leading zeros are considered), that's why we search for odd numbers 2n-1 their smallest multiple k(2n-1) which is palindromic in base 2. Obviously this must always be odd.
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FORMULA
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a(n)=(2n-1)*A141707(n)
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PROGRAM
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(PARI) A141708(n, L=10^9)={ n=2*n-1; forstep(k=1, L, 2, binary(k*n)-vecextract(binary(k*n), "-1..1")|return(k*n))}
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CROSSREFS
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Cf. A050782, A141707, A062279.
Sequence in context: A135773 A131668 A119252 this_sequence A081434 A007632 A117996
Adjacent sequences: A141705 A141706 A141707 this_sequence A141709 A141710 A141711
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KEYWORD
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base,easy,nice,nonn
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AUTHOR
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M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Jul 17 2008
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