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A071416 GCD(n, binomial(2*n, n)). 2
1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 4, 1, 2, 15, 2, 1, 6, 1, 20, 3, 2, 1, 12, 1, 2, 1, 28, 1, 2, 1, 2, 3, 2, 7, 4, 1, 2, 1, 20, 1, 42, 1, 4, 45, 2, 1, 12, 1, 2, 3, 4, 1, 6, 1, 8, 3, 2, 1, 12, 1, 2, 3, 2, 5, 66, 1, 4, 3, 10, 1, 36, 1, 2, 15, 4, 77, 6, 1, 20, 1, 2, 1, 28, 5, 2, 3, 88, 1, 10, 91, 4, 1, 2, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) = n for n in A014847. - Reinhard Zumkeller

a(n) = gcd(n, C(n)), C(n) the Catalan numbers. - Peter Luschny Oct 06 2011

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

Eric Weisstein's World of Mathematics, Central Binomial Coefficient

EXAMPLE

a(10) = GCD(10, binomial(20, 10)) = GCD(10, 184756) = 2.

MATHEMATICA

Table[GCD[n, Binomial[2n, n]], {n, 100}] (* Harvey P. Dale, Nov 10 2011 *)

CROSSREFS

Cf. A000984, A000108.

Sequence in context: A324605 A086545 A126083 * A053589 A055770 A225821

Adjacent sequences:  A071413 A071414 A071415 * A071417 A071418 A071419

KEYWORD

nonn,nice

AUTHOR

Reinhard Zumkeller, May 29 2002

STATUS

approved

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Last modified September 15 14:04 EDT 2019. Contains 327078 sequences. (Running on oeis4.)