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Search: id:A039004
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| A039004 |
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Numbers n such that representation in base 4 has same number of 1's and 2's. |
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+0
11
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| 0, 3, 6, 9, 12, 15, 18, 24, 27, 30, 33, 36, 39, 45, 48, 51, 54, 57, 60, 63, 66, 72, 75, 78, 90, 96, 99, 102, 105, 108, 111, 114, 120, 123, 126, 129, 132, 135, 141, 144, 147, 150, 153, 156, 159, 165, 177, 180, 183, 189, 192, 195, 198, 201, 204, 207, 210, 216, 219
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Numbers such that sum (-1)^k*b(k) = 0 where b(k)=k-th binary digit of n. - Benoit Cloitre (benoit7848c(AT)orange.fr), Nov 18 2003
Conjecture: a(C(2n,n)-1) = 4^n - 1. (A000984 is C(2n,n). - Gerald McGarvey (gerald.mcgarvey(AT)comcast.net), Nov 18 2007
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FORMULA
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Conjecture : there is a constant c around 5 such that a(n) is asymptotic to c*n. - Benoit Cloitre, Nov 24, 2002
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PROGRAM
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(PARI) for(n=0, 219, if(sum(i=1, length(binary(n)), (-1)^i*component(binary(n), i))==0, print1(n, ", ")))
See link in A139351 for Fortran program.
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CROSSREFS
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Cf. A139370-A139373, A139351-A139355.
Sequence in context: A138252 A102796 A028251 this_sequence A070021 A083354 A135943
Adjacent sequences: A039001 A039002 A039003 this_sequence A039005 A039006 A039007
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KEYWORD
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nonn,base,easy
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AUTHOR
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Olivier Gerard (olivier.gerard(AT)gmail.com)
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