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%I #15 Feb 14 2014 07:50:27
%S 1,2,1,5,35,385,715,12155,46189,1062347,30808063,955049953,1859834119,
%T 76253198879,298080686527,14009792266769,742518990138757,
%U 43808620418186663,86204059532560853,339745411098916303,24121924188023057513,47591904479072518877,3759760453846728991283
%N Denominator of product_{k=1..n-1} (1 + 1/prime(k)).
%D G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers, 5th ed., Oxford Univ. Press, 1979; Theorem 429.
%H Vincenzo Librandi, <a href="/A236436/b236436.txt">Table of n, a(n) for n = 1..200</a>
%H J. Sondow and E. Weisstein, <a href="http://mathworld.wolfram.com/MertensTheorem.html">MathWorld: Mertens Theorem</a>
%F A236435(n+1) / a(n+1) = A072045(n)/A072044(n) / A038110(n+1)/A060753(n+1) because 1+x = (1-x^2) / (1-x).
%F A236436(n) / a(n) = product_{k=1..n-1} (1 + 1/prime(k)) ~ (6/Pi^2)*exp(gamma)*log(n) as n -> infinity, by Mertens' theorem.
%e (1 + 1/2)*(1 + 1/3)*(1 + 1/5)*(1 + 1/7) = 96/35 has denominator a(5) = 35.
%t Denominator@Table[Product[1 + 1/Prime[k], {k, 1, n - 1}], {n, 1, 23}]
%Y Cf. A038110, A060753, A072044, A072045, A236435.
%K nonn,frac
%O 1,2
%A _Jonathan Sondow_, Feb 01 2014