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A090586 Denominator of Sum/Product of first n numbers. 10
1, 2, 1, 12, 8, 240, 180, 1120, 8064, 725760, 604800, 79833600, 68428800, 830269440, 10897286400, 2615348736000, 2324754432000, 711374856192000, 640237370572800, 11585247657984000, 221172909834240000, 102181884343418880000, 93666727314800640000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

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

LINKS

Robert Israel, Table of n, a(n) for n = 1..451

MAPLE

seq(denom((n+1)/(2*(n-1)!)), n=1..25); # Robert Israel, Oct 14 2018

MATHEMATICA

Table[Denominator[(n + 1) / (2 (n - 1)!)], {n, 25}] (* Vincenzo Librandi, Oct 15 2018 *)

PROG

(MAGMA) [Denominator(n + 1) / (2*Factorial(n - 1)): n in [1..30]]; // Vincenzo Librandi, Oct 15 2018

CROSSREFS

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

Sequence in context: A058843 A130559 A135256 * A268512 A217109 A297967

Adjacent sequences:  A090583 A090584 A090585 * A090587 A090588 A090589

KEYWORD

nonn,frac

AUTHOR

Reinhard Zumkeller, Dec 03 2003

STATUS

approved

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Last modified August 8 02:22 EDT 2020. Contains 336290 sequences. (Running on oeis4.)