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a(n) = (2^n - 1)^3 - 2.
4

%I #21 Mar 13 2024 10:49:14

%S -2,-1,25,341,3373,29789,250045,2048381,16581373,133432829,1070599165,

%T 8577357821,68669157373,549554511869,4397241253885,35181150961661,

%U 281462092005373,2251748274470909,18014192351838205

%N a(n) = (2^n - 1)^3 - 2.

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (15,-70,120,-64).

%F G.f.: (136*x^3-100*x^2+29*x-2) / ((x-1)*(2*x-1)*(4*x-1)*(8*x-1)). - _Colin Barker_, Apr 30 2013

%e a(2) = (2^2 - 1)^3 - 2 = 25.

%t Table[(2^n - 1)^3 - 2, {n, 0, 20}] (* _Stefan Steinerberger_, Feb 15 2006 *)

%t (2^Range[0,20]-1)^3-2 (* or *) LinearRecurrence[{15,-70,120,-64},{-2,-1,25,341},30] (* _Harvey P. Dale_, Jan 29 2016 *)

%o (PARI) a(n) = (2^n - 1)^3 - 2; \\ _Joerg Arndt_, Apr 30 2013

%Y See A091515.

%K sign,easy

%O 0,1

%A _Parthasarathy Nambi_, Oct 13 2004

%E More terms from _Stefan Steinerberger_, Feb 15 2006