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4^n! - 3^n! + 2^n! - 1.
0

%I #11 Nov 04 2017 18:33:27

%S 2,2,10,3430,281192563951390,

%T 1766847064778382532572997586311708103976882383055495099549785723721857950

%N 4^n! - 3^n! + 2^n! - 1.

%C The next term has 434 digits. - _Harvey P. Dale_, Nov 04 2017

%F a(n)=4^n!-3^n!+2^n!-1.

%e For n=2, a(2)=4^2!-3^2!+2^2!-1=16-9+4-1=10.

%t 4^#-3^#+2^#-1&/@(Range[0,5]!) (* _Harvey P. Dale_, Nov 04 2017 *)

%o (PARI) a(n)=(k->4^k-3^k+2^k-1)(n!) \\ _Charles R Greathouse IV_, Jan 23 2014

%Y Cf. A203925, A236368.

%K nonn

%O 0,1

%A _Assoul Abdelkarim_, Jan 23 2014

%E a(4)-a(5) from _Charles R Greathouse IV_, Jan 23 2014