This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A037239 Numerator of Pi^(2n)/(GAMMA(2n)*(1-2^(-2n))*Zeta(2n)); = 8*(highest power of 2 dividing n). 2

%I

%S 8,16,8,32,8,16,8,64,8,16,8,32,8,16,8,128,8,16,8,32,8,16,8,64,8,16,8,

%T 32,8,16,8,256,8,16,8,32,8,16,8,64,8,16,8,32,8,16,8,128,8,16,8,32,8,

%U 16,8,64,8,16,8,32,8,16,8,512,8,16,8,32,8,16,8,64,8

%N Numerator of Pi^(2n)/(GAMMA(2n)*(1-2^(-2n))*Zeta(2n)); = 8*(highest power of 2 dividing n).

%H Antti Karttunen, <a href="/A037239/b037239.txt">Table of n, a(n) for n = 1..16384</a>

%H Harvey Cohn, <a href="http://dx.doi.org/10.1090/S0002-9904-1965-11343-X">Some elementary aspects of modular functions in several variables</a>, Bull. Amer. Math. Soc. 71 (1965), 681-704, (esp. p. 688).

%p with(numtheory): for n from 1 to 200 do if n mod 2 = 1 then printf(`%d,`,8) else printf(`%d,`,8*2^ifactors(n)[2][1][2]) fi; od:

%p seq(2^(3+padic[ordp](n,2)), n=1..73); # _Peter Luschny_, Apr 03 2014

%t a[n_] := 8*BitAnd[n, -n]; Table[a[n], {n, 1, 81}] (* _Jean-François Alcover_, Sep 20 2011, after _Joerg Arndt_ *)

%o (PARI) a(n)=if(n<1,0,8*2^valuation(n,2))

%o (MAGMA) [2^(3 + Valuation(n,2)): n in [1..80]]; // _G. C. Greubel_, Nov 01 2018

%Y Equals 8*A006519. Denominators given by A002425.

%K nonn,frac,easy

%O 1,1

%A _N. J. A. Sloane_

%E More terms from _James A. Sellers_, Jun 20 2000

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 22 18:51 EST 2019. Contains 319365 sequences. (Running on oeis4.)