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 A090586 Denominator of Sum/Product of first n numbers. 10

%I

%S 1,2,1,12,8,240,180,1120,8064,725760,604800,79833600,68428800,

%T 830269440,10897286400,2615348736000,2324754432000,711374856192000,

%U 640237370572800,11585247657984000,221172909834240000,102181884343418880000,93666727314800640000

%N Denominator of Sum/Product of first n numbers.

%C a(n) = A000142(n)/A069268(n);

%C a(p-1) = 2*A000142(p-2) for odd primes.

%H Robert Israel, <a href="/A090586/b090586.txt">Table of n, a(n) for n = 1..451</a>

%p seq(denom((n+1)/(2*(n-1)!)),n=1..25); # _Robert Israel_, Oct 14 2018

%t Table[Denominator[(n + 1) / (2 (n - 1)!)], {n, 25}] (* _Vincenzo Librandi_, Oct 15 2018 *)

%o (MAGMA) [Denominator(n + 1) / (2*Factorial(n - 1)): n in [1..30]]; // _Vincenzo Librandi_, Oct 15 2018

%Y Cf. A090585 (numerator). Main diagonal of A093420.

%K nonn,frac

%O 1,2

%A _Reinhard Zumkeller_, Dec 03 2003

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Last modified August 14 07:04 EDT 2020. Contains 336477 sequences. (Running on oeis4.)