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A265401
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Numbers n for which gcd{k=1..n-1} binomial(2*n, 2*k) = 1.
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2
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20, 26, 33, 35, 38, 39, 44, 46, 48, 50, 56, 58, 60, 62, 68, 72, 74, 77, 78, 80, 86, 88, 92, 93, 94, 95, 98, 102, 104, 105, 108, 110, 111, 116, 118, 119, 124, 130, 133, 134, 138, 140, 143, 144, 146, 148, 150, 152, 155, 158, 160, 161, 164, 165, 168, 170, 171, 176, 178, 182, 183, 185, 186, 188, 189, 194, 198, 200
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OFFSET
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1,1
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COMMENTS
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LINKS
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MAPLE
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select(n -> igcd(seq(binomial(2*n, 2*k), k=1..n-1)) = 1, [$1..200]); # Robert Israel, Dec 10 2015
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MATHEMATICA
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Select[Range@ 200, GCD @@ Table[Binomial[2 #, 2 k], {k, # - 1}] == 1 &] (* Michael De Vlieger, Dec 09 2015, modified to match the new corrected definition by Antti Karttunen, Dec 11 2015 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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