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A023969
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Round(sqrt(n)) - floor(sqrt(n)).
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2
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0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| First bit in fractional part of binary expansion of square root of n.
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FORMULA
| Runs are 0^1, 0^2 1, 0^3 1^2, 0^4 1^3, ...
a(n) = 1 iff n >= 3 and n is in the interval [k*(k+1) + 1, ..., k*(k+1) + k] for some k >= 1.
a(n) = floor(2*sqrt(n))-2*floor(sqrt(n)). [Mircea Merca, Jan 31 2012]
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MATHEMATICA
| Array[ Function[ n, RealDigits[ N[ Power[ n, 1/2 ], 10 ], 2 ]// (#[ [ 1, #[ [ 2 ] ]+1 ] ])& ], 110 ]
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PROG
| (PARI) a(n)=sqrtint(4*n)-2*sqrtint(n) \\ Charles R Greathouse IV, Jan 31 2012
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CROSSREFS
| Cf. A080343, A080344.
Sequence in context: A129251 A144602 A160351 * A060039 A107078 A163533
Adjacent sequences: A023966 A023967 A023968 * A023970 A023971 A023972
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Olivier Gerard (olivier.gerard(AT)gmail.com)
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EXTENSIONS
| Revised by N. J. A. Sloane (njas(AT)research.att.com), Mar 20 2003.
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