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Search: id:A161400
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| A161400 |
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Positive integers that are palindromes (of even length) in binary, each made by concatenating two identical binary palindromes. |
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+0
1
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| 3, 15, 45, 63, 153, 255, 561, 693, 891, 1023, 2145, 2925, 3315, 4095, 8385, 9417, 10965, 11997, 12771, 13803, 15351, 16383, 33153, 39321, 42405, 48573, 50115, 56283, 59367, 65535, 131841, 140049, 152361, 160569, 166725, 174933, 187245
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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If m is the n-th positive integer that is a binary palindrome, and m written in binary is k digits long, then a(n) = m*(2^k +1).
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FORMULA
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a(n) = (2^A070939(p)+1)*p where p = A006995(n+1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 27 2009]
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EXAMPLE
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The first eight terms of this sequence written in binary:
11, 1111, 101101, 111111, 10011001, 11111111, 1000110001, 1010110101
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CROSSREFS
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A006995
Sequence in context: A147057 A101165 A127407 this_sequence A112810 A094191 A050534
Adjacent sequences: A161397 A161398 A161399 this_sequence A161401 A161402 A161403
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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 09 2009
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EXTENSIONS
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Extended beyond 693 by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 27 2009
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