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A082916
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Numbers k such that k and binomial(2*k, k) are relatively prime.
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3
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0, 1, 3, 5, 7, 9, 11, 13, 17, 19, 23, 25, 27, 29, 31, 37, 39, 41, 43, 47, 49, 53, 55, 59, 61, 67, 71, 73, 79, 81, 83, 89, 93, 97, 101, 103, 107, 109, 111, 113, 119, 121, 125, 127, 131, 137, 139, 149, 151, 155, 157, 161, 163, 167, 169, 173, 179, 181, 185, 191, 193, 197
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OFFSET
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1,3
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LINKS
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FORMULA
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It seems that a(n) is asymptotic to c*n*log(n) with 0.7<c<0.8.
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MATHEMATICA
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Select[Range[0, 100], CoprimeQ[Binomial[2*#, #], #] &] (* Amiram Eldar, May 24 2020 *)
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PROG
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(PARI) isok(n) = gcd(n, binomial(2*n, n)) == 1; \\ Michel Marcus, Dec 04 2013
(Python)
from __future__ import division
from fractions import gcd
for n in range(10**5):
if gcd(n, b) == 1:
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CROSSREFS
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Cf. A000984 (central binomial coefficients).
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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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