A293459 - OEIS

%I #13 Sep 21 2019 08:26:24

%S 1,1,7,385,3628921,1216452311762688721,

%T 10333147966386144929717742279694909445041,

%U 5989285834984945898036392571843137173092920925318860392502631168811983977451725959000900501504040321

%N Denominator of probability that a permutation of elements of some subset of set {1,2..n} is a permutation of elements of some set of the form 1..k, k <= n.

%H Amiram Eldar, <a href="/A293459/b293459.txt">Table of n, a(n) for n = 1..10</a>

%t a[n_] := Denominator[Sum[k!, {k, 0, n}]/Sum[Binomial[n, k]!, {k, 0, n}]]; Array[a, 8] (* _Amiram Eldar_, Sep 21 2019 *)

%o (PARI) a(n) = denominator(sum(k=0, n, k!)/sum(k=0, n, binomial(n,k)!)); \\ _Michel Marcus_, Oct 12 2017

%Y Cf. A293458(numerators).

%K nonn,frac

%O 1,3

%A _Vladimir Shevelev_, Oct 09 2017

%E More terms from _Peter J. C. Moses_, Oct 09 2017