A004786 - OEIS

%I #12 Aug 03 2014 14:27:51

%S 4,6,7,991,2481,3479,6163,6581,8178,8179,9272,10288,12195,13067,13976,

%T 15199,15813,16172,18371,18686,18723,18747,19294,19438,19506,23531,

%U 26198,26315,26678,27877,28429,30553,30593,30689,31327,31375,32882,33006,33451

%N 6!(2n-7)!/n!(n-1)! is an integer.

%t Select[Range[10^4], IntegerQ[6! (2 # - 7)!/(#! (# - 1)!)] &] (* _Arkadiusz Wesolowski_, Sep 06 2011 *)

%K nonn

%O 1,1

%A _R. K. Guy_

%E More terms from David W. Wilson, Dec 11 1999

%E Offset corrected and 2 initial terms added by Arkadiusz Wesolowski, Sep 06 2011