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A048618 Even numbers n such that binomial(n,n/2) is divisible by n/2. 2

%I

%S 2,4,12,30,40,56,84,90,132,154,176,182,208,220,252,280,306,312,340,

%T 374,380,408,418,420,440,456,462,476,480,532,552,598,616,624,630,644,

%U 650,660,690,736,756,828,840,858,870,880,884,900,918,920,928,936,952,966

%N Even numbers n such that binomial(n,n/2) is divisible by n/2.

%H Rémy Sigrist, <a href="/A048618/b048618.txt">Table of n, a(n) for n = 1..10000</a>

%H M. Alekseyev, <a href="http://home.gwu.edu/~maxal/gpscripts/">PARI/GP Scripts for Miscellaneous Math Problems</a>, sect. III: Binomial coefficients modulo integers, binomod.gp (V. 1.4, 11/2015).

%F a(n) = 2 * A014847(n). - _Rémy Sigrist_, Aug 27 2017

%e For n=30, binomial(30,15) = 155117520 = 15^10341168, so 30 is a term.

%p a:=[];

%p for n from 1 to 1000 do if ( binomial(2*n,n) mod n ) = 0 then a:=[op(a),2*n]; fi; od;

%p a; # _N. J. A. Sloane_, Aug 03 2017

%Y Cf. A001405, A020475, A014847, A067348 (binomial(2*n,n) is divisible by 2*n).

%K nonn

%O 1,1

%A _Labos Elemer_

%E Definition corrected by _N. J. A. Sloane_, Aug 03 2017

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Last modified April 7 10:56 EDT 2020. Contains 333301 sequences. (Running on oeis4.)