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 A024502 a(n) = floor(C(2n,n)/2^n). 1

%I

%S 1,1,1,2,4,7,14,26,50,94,180,344,660,1269,2448,4733,9171,17804,34618,

%T 67415,131460,256661,501656,981501,1922106,3767329,7389761,14505829,

%U 28493592,56004648,110142474,216731966,426691058,840452084,1656184990

%N a(n) = floor(C(2n,n)/2^n).

%F For n>0, a(n) = floor(A006882(2*n-1) / n!). - _Alex Ratushnyak_, Nov 28 2013

%e a(4) = floor(1*3*5*7 / (1*2*3*4)) = floor(35/8) = 4.

%t Table[Floor[Binomial[2n,n]/2^n],{n,0,40}] (* _Harvey P. Dale_, Mar 07 2016 *)

%o (Python) import math

%o for n in range(55): print str(math.factorial(2*n)//(math.factorial(n)**2 * 2**n))+',',

%o # _Alex Ratushnyak_, Nov 28 2013

%o (PARI) a(n)=binomial(2*n,n)>>n \\ _Charles R Greathouse IV_, Jul 19 2016

%Y Cf. A006882.

%K nonn

%O 0,4

%A _Clark Kimberling_

%E More terms from _Benoit Cloitre_, Jan 26 2002

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Last modified September 30 05:03 EDT 2020. Contains 337435 sequences. (Running on oeis4.)