A061370 a(n) = floor(ratio of product and sum of first n numbers).
1, 0, 1, 2, 8, 34, 180, 1120, 8064, 65978, 604800, 6141046, 68428800, 830269440, 10897286400, 153844043294, 2324754432000, 37440781904842, 640237370572800, 11585247657984000, 221172909834240000, 4442690623626907826
Offset: 1
Examples
a(6) = floor(720/21) = 34.
Links
- Harry J. Smith, Table of n, a(n) for n = 1..100
Programs
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Maple
a:=n->floor(mul(j,j=1..n)/sum(j,j=1..n)):seq(a(n),n=1..23); # Zerinvary Lajos, Dec 07 2008
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Mathematica
Table[ Floor[2*(n - 1)!/(n + 1)], {n, 1, 24} ] -
PARI
a(n) = { 2*(n-1)! \ (n+1) } \\ Harry J. Smith, Jul 22 2009
Formula
a(n) = floor(2*(n-1)! / (n+1)).
Extensions
More terms from Larry Reeves (larryr(AT)acm.org), May 07 2001