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a(n) = (n!)^2 - 1.
2

%I #18 Sep 08 2022 08:44:56

%S 0,3,35,575,14399,518399,25401599,1625702399,131681894399,

%T 13168189439999,1593350922239999,229442532802559999,

%U 38775788043632639999,7600054456551997439999,1710012252724199423999999,437763136697395052543999999,126513546505547170185215999999

%N a(n) = (n!)^2 - 1.

%H Vincenzo Librandi, <a href="/A046032/b046032.txt">Table of n, a(n) for n = 1..100</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Factorial.html">Factorial</a>

%t Table[(n!)^2-1,{n,30}] (* _Vladimir Joseph Stephan Orlovsky_, May 19 2011 *)

%o (PARI) a(n)=n!^2-1 \\ _Charles R Greathouse IV_, Sep 19 2012

%o (Magma) [Factorial(n)^2-1: n in [1..15]]; // _Vincenzo Librandi_, Jun 03 2013

%Y Cf. A001044.

%K nonn,easy

%O 1,2

%A _Eric W. Weisstein_